Snorkeling in Mexico: reefs, cenotes, Cozumel and Cabo Pulmo

“Snorkeling in Mexico” is one search phrase describing four different trips. There is the Riviera Maya — the Caribbean reef coast everybody means by default. There is the cenote water a few kilometers inland of it, which is fresh, cave-filtered, 75 degrees and unlike anything else on earth. There is Cozumel, which is an island, a ferry and a boat day with the clearest reef water in the country. And there is Baja California, on the other ocean entirely, where a village that hung up its fishing nets created the richest water Mexico has.

I grew up in Caribbean water in Puerto Rico, spent over ten years in the Key West charter trade putting snorkelers onto a reef for a living, and I have traveled enough of the Mexican coast to know the mistake almost everyone makes here: they rank when they should route. You do not pick “the best snorkeling in Mexico.” You pick which of the four trips fits the week you actually have — and then you learn its rules, because the rules are most of what has changed. Akumal put its turtles behind licensed guides. The federal marine-park bracelets doubled in price in January 2025. The cenote gates have raised prices nearly every season. And the reef itself came through the worst bleaching ever recorded on this coast.

All of that is below, with current prices, dated. This is a page about getting the right morning in the right water, which is the only version of this topic worth writing.

Where the sites are

The Caribbean side is one straight decision. A single highway runs south from Cancún airport: Puerto Morelos at about half an hour, Playa del Carmen at an hour, Akumal at ninety minutes, Tulum at about two hours. The snorkeling cenotes sit just off that same road, mostly in the last stretch before Tulum. Cozumel is a 30-to-45-minute ferry from Playa del Carmen, running every half hour from 8 a.m. at roughly US$12–16 each way.¹ Isla Mujeres is a short ferry from Cancún. Base yourself anywhere on the corridor and every Caribbean site on this page is a day trip.

Baja is not on that map. Cabo Pulmo is a flight to Los Cabos and a two-hour drive up the East Cape — a different ocean, a different trip, and for the right person the better one.

Site	The trip	The rule that matters	Cost of entry (checked 8 August 2026)
Dos Ojos	Cenotes	Bat Cave only with the guided tour; cash only	400 MXN, or 800 with tour2
Gran Cenote	Cenotes	Mandatory shower; last entry 4:15 p.m.; cash	500 MXN incl. jacket and gear3
Casa Cenote	Cenotes	Open lagoon; resident crocodile; cash	500 MXN4
Akumal Bay	Riviera reef	Turtle zone is guided-only, vest required, max 6 per guide	US$25–40 guided session5
Puerto Morelos	Riviera reef	Boat and guide only — no swimming out; life jacket mandatory	Tours from ~US$256
El Cielo / Palancar, Cozumel	Cozumel boat day	Licensed boats only; no standing on the sandbar	Park bracelet 218.32 MXN/day7
MUSA / Manchones	Isla Mujeres	Snorkel gallery is Punta Nizuc (2–4 m); Manchones is deeper	Inside tour pricing8
Whale sharks	Isla Mujeres, summer	Season May 15 – Sep 15; boats really start June 1	Tour-priced, permitted boats9
Cabo Pulmo	Baja	No-take park; fee collected per day	125 MXN/day10

The reef, honestly

The Mesoamerican Reef is the second-largest barrier reef system in the world, running more than 600 miles down Mexico, Belize, Guatemala and Honduras.¹¹ Mexico holds its northern end, and you should know what shape that end is in, because no tour desk will tell you.

The 2023–24 global bleaching event hit this system harder than anything on record. The 2024 Mesoamerican Reef Report Card grades the reef poor, with regional coral cover down from 19 to 17 percent between 2022 and 2024 and roughly 40 percent of corals severely affected by what it calls the worst bleaching event to date.¹² At Puerto Morelos the numbers are brutal and specific: the 2023 heatwave drove inshore water to nearly 35 °C — 4.8 degrees above normal — and by August 2023, 57 percent of the elkhorn coral was already dead and the rest bleached. By July 2024, surveys found no living elkhorn there at all.¹³

Here is the counterweight, and it is not spin: the same report card recorded the reef’s first health improvement in five years, on fish. Commercial fish biomass is up 40 percent since 2022 and herbivores up 30 percent, on genuinely better enforcement.¹⁴ I have watched a reef through hard years before — the Florida Keys reef I worked and speared for the better part of a decade has its own version of this story — and the practical reading for a snorkeler is the same in both places: go for the fish, the rays, the turtles and the structure, which are emphatically still there, and stop expecting the wall-to-wall living color of the postcards. It also changes the routing. The sand-and-fish spectacles like El Cielo, the freshwater cenotes and Baja’s Cabo Pulmo now carry more of a Mexico trip than the coral gardens do — which is exactly how this page is weighted. The same honest arithmetic applies down the reef in Belize and Roatán.

The cenotes — the trip you cannot take anywhere else

The Yucatán has no rivers on the surface. Its fresh water moves through limestone underground, and where the cave roof has collapsed you get a cenote — a window into the aquifer, filled with rainwater filtered through rock. The result is visibility no sea can match, stone formations instead of coral, shafts of jungle light instead of fish, and water that holds 75–77 °F every day of the year.¹⁵ It is cold after your first half hour; a neoprene top solves it, and what to wear snorkeling covers the choice.

Three cenotes make the snorkeling shortlist, and they are usefully different:

Dos Ojos, north of Tulum, is the cathedral — two collapsed “eyes” opening into one of the longest underwater cave systems in the world. Entry is 400 pesos with a life jacket included, cash only, and the guided snorkel tour at 800 pesos is the only way into the Bat Cave, which is the best thing in the water here and worth the difference.² Gates open at 8 a.m.; be there then, because the tour vans arrive by mid-morning.¹⁵

Gran Cenote, minutes from Tulum, is the friendly one — open pools, boardwalks, small freshwater turtles, easy entries. 500 pesos includes jacket and snorkel gear; there is a mandatory rinse-off shower, a hard ban on sunscreen, and last entry at 4:15 p.m. Cash again.³

Casa Cenote is the strange one, and my kind of strange: a mangrove-lined channel where the aquifer meets the sea, about six meters deep, so fresh and salt water layer and blur into each other — swim through the halocline and the water goes wobbly like oil over glass. Entry has climbed to 500 pesos, life jacket included, and yes, there is a resident crocodile named Panchito; the operators treat him as furniture.⁴ Kayaks and paddleboards rent at the gate.

If you would rather have the logistics handled, a private Dos Ojos snorkel tour with a Mayan lunch does hotel pickup from Playa del Carmen or Tulum, runs the caves with your own guide and solves the cash-gate problem in one booking. Do one cave cenote and one open cenote rather than three of the same kind — the third cave adds nothing the first two didn’t.

Akumal Bay — the turtles are behind guides now

Akumal means “place of the turtles,” and the shallow seagrass that feeds green turtles a few fin-kicks off the sand made it the most loved — and most trampled — snorkel beach on the Riviera Maya. The regulator’s answer is the current regime, and it is worth stating exactly, because the beach-bar version you will hear is wrong: the turtle zone is buoyed off, you enter it only with a licensed guide, in a vest, in a group of six or fewer, for a session of about 45 to 55 minutes, in daylight hours, keeping three meters off the animals. Guided sessions cost about US$25–40 per person, booked right on the beach.⁵ There are no guided tours on Mondays — plan turtles for any other morning.¹⁶ Outside the buoys you can still swim free from the public access at the north end.

I ran boats in a place where the rules tightened year over year, and I will tell you how to read this one: a cap of six snorkelers to a guide is not a money grab, it is what keeps a feeding animal feeding while four hundred people a day come to look at it. Book the early session, before the day-trip buses arrive around ten, and you get calm water, best light and turtles behaving like nobody is watching.

Pair it with Yal-Ku, the lagoon at Akumal’s north end where the aquifer drains to the sea — sheltered, current-free and easy. Life jackets are mandatory, only chemical-free sunscreen is allowed, and it runs 9 a.m. to 5 p.m.¹⁷ For staying: Las Casitas Akumal puts you on the quiet end of the bay itself, which is how you make the 8 a.m. session without driving for it.

Cozumel — the clearest water, one ferry away

Cozumel is where the Mexican Caribbean is clearest, for a reason a chart makes obvious: the island’s developed west coast sits in the lee, sheltered from the open sea, with current-swept water moving along a steep shelf. The same geometry keeps its west side largely clean of sargassum even in heavy summers,¹⁸ which makes Cozumel the reef day that still works in July.

The crossing from Playa del Carmen takes 30 to 45 minutes, boats every half hour from 8 a.m., about US$12–16 each way — commit to the first sensible ferry and you are in the water before the cruise-ship crowds are ashore.¹ Sit up top on the open deck; it is a real strait, and I have watched enough green faces on morning crossings to promise you the fresh air is worth more than the air conditioning.

The snorkeling that justifies the trip is at the island’s south end, inside the reefs national park, and it is boat snorkeling: El Cielo, a meter-deep sandbar scattered with starfish over impossibly blue water — no standing, no touching, licensed boats only — and the shallow sections of Colombia and Palancar, the famous reef names, where the coral structure rises close enough to the surface to matter.¹⁹ The federal park bracelet doubled to 218.32 pesos per day on 1 January 2025; your operator collects it, in cash, on top of the tour.⁷ A typical El Cielo run prices around 1,850 pesos.¹⁹ An all-inclusive El Cielo snorkel tour covering the park reefs and the sandbar is the standard shape of the day.

Puerto Morelos — the honest reef day

Half an hour south of Cancún airport, Puerto Morelos is a working port town in front of a national park, and it runs the most honest reef operation on the corridor. The reef sits about 400 meters offshore; you cannot swim out to it, and you cannot snorkel it unguided — it is a boat, a guide and a mandatory life jacket, with trips leaving from the town pier from about US$25 for a two-hour, two-stop run over channels about six meters deep, with rays, turtles and reef fish over the sand.⁶

This is the same small-boat economy I worked in for a decade, and Puerto Morelos runs the best version of it: the boats take turns, the price is posted at the pier, and the man selling the trip is frequently the man driving it. Buy at the pier in the morning, or book the small-group Puerto Morelos snorkel with park entry included if you want hotel pickup from Cancún.

Be clear-eyed about what you are swimming over. Puerto Morelos is where the 2023 heat did its documented worst — the elkhorn stands that made this park’s name are gone.¹³ What is left is a protected, patrolled fish habitat with easy conditions and short logistics, and as a half-day with kids it still beats anything in the Cancún hotel zone. For an adults-only base right here, Excellence Riviera Cancun sits on the beach just north of town.

Isla Mujeres and MUSA — statues, reef and the summer giants

MUSA, the underwater sculpture museum between Cancún and Isla Mujeres, holds more than 500 figures deliberately sunk as an artificial reef, and the depth decides your experience: the Punta Nizuc gallery lies in two to four meters — genuine snorkeling, faces and details close under you — while the main Manchones gallery sits at eight to ten meters, built for divers, with snorkelers watching the crowd scene from the surface.⁸ The right way to do it from the island is a three-stop boat that pairs the statues with the Manchones reef itself — this Isla Mujeres snorkel tour with lunch is that day, capped at fifteen people.

Summer adds the giants. Whale sharks aggregate in the open water off Isla Mujeres inside an official season of May 15 to September 15, but the serious operators do not start running until June 1, when the animals show reliably, and July and August are the peak.⁹ It is an open-ocean swim from permitted boats — no reef, no shade, early starts — and it is the single best in-water wildlife encounter on Mexico’s Caribbean coast. A small-group whale shark snorkel from Cancún with a biologist on board is the standard booking. If your dates land in late June through August, plan the rest of the trip around this day, not the other way round.

Cabo Pulmo — the recovery story worth flying for

Now the other ocean. Cabo Pulmo, on Baja’s East Cape in the Sea of Cortez — the body of water Jacques Cousteau called “the aquarium of the world”²⁰ — is a village that fished its reef to exhaustion, stopped, and won. After the no-take national park was declared in 1995, fish biomass inside it rose 463 percent in a decade, with top predators up more than tenfold — the strongest recovery ever measured in a marine reserve, which is why Scripps researchers call it the most robust marine protected area in the world.²¹

What that means with a mask on: bait balls, big jacks in schools that block the light, groupers, turtles, and a density of life the Caribbean side simply does not have anymore. The park charges 125 pesos per person per day — children under 12, seniors and visitors with disabilities exempt — runs 8 a.m. to 6 p.m., and sits about 98 kilometers from San José del Cabo via La Ribera.¹⁰ The good sites are boat sites, with pangas running from the village; Los Arbolitos, south of town, is the shore-entry fallback. From the Cabo San Lucas resorts it is a committed day — a Cabo Pulmo snorkel expedition with a two-hour drive each way and up to four sites in between, capped at eight people. Better: sleep out east. Vidasoul, on the empty coast south of the park, is the kind of end-of-the-road base the East Cape is for. With more Baja days, La Paz and Isla Espíritu Santo up the coast are the other reason to bring a mask to this side of the country.

When to go, month by month

Sea temperature is never the problem here — the Riviera Maya runs 81 °F in the coolest months and 86 °F at the summer peak.²² What decides your trip is sargassum on the mainland’s east-facing beaches, storm season, and the whale-shark calendar.

Month	Water22	Mainland sargassum23	Call it
January	81 °F	Clear	Excellent everywhere
February	81 °F	Clear	The best month, full stop
March	81 °F	Clear to light	Excellent; spring-break crowds
April	81 °F	First arrivals	Very good, closing window
May	82 °F	Building	Cozumel and cenotes carry the trip
June	84 °F	Heavy	Whale sharks; leeward Cozumel; cenotes
July	84 °F	Heaviest	Whale sharks at peak; route around the weed
August	86 °F	Heavy	Whale sharks; hurricane risk rising
September	86 °F	Easing	Peak storm risk; empty and cheap
October	86 °F	Easing north of Playa	Storm lottery; improving late
November	84 °F	Mostly clear	The quiet gem of the calendar
December	82 °F	Clear	Excellent; holiday pricing

Two 2026-specific things. This sargassum year is tracking toward a record — beaching started as early as January, and the University of South Florida’s monitoring has flagged a possible all-time high by late summer²³ — so the summer routing above matters more than usual. And the routing works because the weed is geographic, not universal: Cozumel’s leeward west side and Isla Mujeres’ west-facing Playa Norte stay clean in even the heavy years, Tulum and Akumal take the worst of it,¹⁸ and the cenotes are inland fresh water that never sees it at all.

What to book, in what order

Pick the trip from the month, not the photograph. December to April, everything on this page works and the corridor is the right base. June to August, build around the whale sharks, do your reef day on Cozumel’s lee side, and spend the hot afternoons underground in the cenotes.

Put the boat days at the front of the trip. Whale sharks, El Cielo and Cabo Pulmo are all weather-cancellable. Booked on day two, a blown-out morning is a reschedule; booked on the last day, it is a refund and a hole in the trip. Ten years of watching dispatch boards taught me that the trip you protect is the one you schedule first.

Reserve the capacity-capped sessions ahead; just show up early for the rest. Akumal’s guides and the whale-shark boats sell out because the caps are real. The cenotes take no reservations worth having — they take an 8 a.m. arrival.

Carry more pesos than feels reasonable. Dos Ojos, Gran Cenote and Casa Cenote are cash-only gates, and the Cozumel park bracelet is cash at the dock.²³⁷ The corridor’s ATMs and I have a long, expensive history; get pesos in town before you drive south.

Mornings, always. The Caribbean breeze builds through the day and puts chop on every exposed site by early afternoon, the tour buses land mid-morning, and the light for seeing into the water is best before eleven. Take the first boat, the first ferry, the first session — the afternoon version of every site on this page is the worse version.

Where to stay, by trip

• Playa del Carmen — the switchboard: mid-corridor for the cenotes and Akumal, and the Cozumel ferry leaves from the middle of town.
• Tulum — closest to the cenote belt; accept that its open beaches take sargassum in summer.
• Cozumel — wake up on the clear side of the water and skip the ferry-day clock entirely.
• Puerto Morelos — the quiet reef-town base, twenty minutes from the airport.

Wherever you land, bring your own mask. Gate-rental gear at the cenotes and beach-stand gear on the corridor is battered and badly fitted, and in 75-degree freshwater a leaking mask ends the swim early. Our travel snorkel gear guide covers sets that pack flat, and the Caribbean overview covers where this coast ranks against the rest of the basin.

Frequently asked questions

What part of Mexico has the best snorkeling?+

Quintana Roo — the Cancún-to-Tulum corridor plus its islands — has the highest concentration: the Mesoamerican Reef offshore, the cenotes inland, Cozumel's marine park across a 45-minute ferry, and the sculpture galleries and summer whale sharks off Isla Mujeres. But the single richest water in the country is on the other coast entirely: Cabo Pulmo, in Baja California Sur, a no-take national park where fish biomass rose 463 percent in the decade after the village stopped fishing it (Scripps Institution of Oceanography). If your trip is built around beaches and ruins, stay Caribbean. If it is built around what you will see underwater, Cabo Pulmo is the strongest answer Mexico has.

Can you swim with the turtles at Akumal on your own?+

Not in the part of the bay where the turtles feed. The seagrass zone is buoyed off as a protected refuge, and entering it requires a licensed guide, a flotation vest, groups of six or fewer, and a session capped at about 45 to 55 minutes (MrPlayas). Guided sessions run about US$25–40 per person, booked at the beach. There are no guided tours on Mondays. You can still swim unguided outside the buoyed zone from the public access at the north end of the beach — but the turtles are the reason you came, and they are inside.

How cold are the cenotes, and do you have to wear a life jacket?+

Cenote water holds about 75–77 °F all year (Tulum Travel Secrets) — refreshing on arrival, genuinely cold after forty minutes of floating without a wetsuit top. Life jackets are included in admission and effectively standard at the snorkeling cenotes: Dos Ojos and Gran Cenote hand them out with your ticket, and Yal-Ku makes wearing one mandatory. Expect a mandatory rinse-off shower before entering and a ban on sunscreen — the water is drinking-water clear because nothing washes into it, and the gates enforce that seriously.

When is the best time to snorkel in Mexico?+

December through April: clear, dry, 81–82 °F in the sea, and before the sargassum arrives on the Caribbean side. May through August brings the heaviest seaweed to the mainland corridor — and 2026 is tracking toward a record year (How Is The Sargassum) — but it is also the only window for whale sharks off Isla Mujeres, and Cozumel's sheltered west coast and the cenotes stay clean regardless. September and October are the hottest water and the peak of storm season. If you can only pick one month, pick February.

Is the reef still worth snorkeling after the coral bleaching?+

Yes — with the picture updated. The 2023–24 marine heatwave was the worst bleaching event ever recorded on the Mesoamerican Reef, with about 40 percent of corals severely affected, and regional coral cover slipped from 19 to 17 percent (Mongabay). At Puerto Morelos, the famous elkhorn stands died outright. What the same report card found improving is the fish: commercial fish biomass up 40 percent and herbivores up 30 percent since 2022 on stronger enforcement (GCRMN). Go for fish, rays, turtles and structure — El Cielo, the Puerto Morelos channels, Cabo Pulmo — and the water still delivers.

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Sources

Footnotes

1. “The Cozumel Ferry: Schedules, Prices.” Cozumel Cruise Tours, 2026 guide, checked 8 August 2026. cozumelcruisetours.com. Playa del Carmen crossings every ~30 minutes from 8 a.m., 30–45 minutes, roughly US$12–16 each way. ↩ ↩²

2. “Cenote Dos Ojos: The Definitive Guide.” Voyage Mexique, updated 29 October 2025, checked 8 August 2026. voyagemexique.info. Entry 400 pesos including life jacket, 800 with the snorkel tour and Bat Cave access; cash only. ↩ ↩² ↩³

3. “The Ultimate Visitor’s Guide to El Gran Cenote Tulum.” Travel Mexico Solo, updated 22 June 2025, checked 8 August 2026. travelmexicosolo.com. Entry 500 pesos including life jacket and snorkel gear; mandatory pre-swim shower; last entry 4:15 p.m.; cash only. ↩ ↩² ↩³

4. “Casa Cenote Tulum.” Let’s Travel to Mexico, updated 30 June 2026, checked 8 August 2026. letstraveltomexico.com. Entry 500 pesos with life jacket included, hours 9 a.m.–5 p.m., ~6 m depth, the resident crocodile. ↩ ↩²

5. “Swim With Turtles in Akumal: Best Time, Rules & Cost.” MrPlayas, checked 8 August 2026. mrplayas.com. Guided-only buoyed zone, mandatory vest, max six snorkelers per guide, ~45–55-minute sessions, US$25–40 guided price, independent swimming only outside the zone. ↩ ↩²

6. “Snorkeling in Puerto Morelos.” Snorkeling Report. snorkeling-report.com. Reef ~400 m offshore, swimming out prohibited, mandatory life jacket, guided boat tours from ~US$25, maximum depth ~6 m, rays and turtles. ↩ ↩²

7. “Price Hike to National Park Fees.” Punta Sur Divers, Cozumel. puntasurdivers.com. Cozumel Reefs National Park daily fee doubled from 108 to 218.32 pesos effective 1 January 2025. ↩ ↩² ↩³

8. “How to Visit the MUSA Underwater Museum: Snorkel vs Dive.” Thoroughly Travel, 28 July 2026. thoroughlytravel.com. 500+ sculptures; Punta Nizuc gallery at 2–4 m for snorkeling; Manchones at 8–10 m, dive-first. ↩ ↩²

9. “Timing Your Whale Shark Tour.” Isla Whale Sharks, updated 29 May 2026. islawhalesharks.com. Technical season 15 May–15 September; operator trips from 1 June; July–August peak. ↩ ↩²

10. “Cabo Pulmo National Park.” CONANP, Mexico’s National Commission of Natural Protected Areas, checked 8 August 2026. descubreanp.conanp.gob.mx. Entry 125 pesos per person per day with exemptions for under-12s, seniors and visitors with disabilities; hours 8 a.m.–6 p.m.; 98.1 km from San José del Cabo via La Ribera. ↩ ↩²

11. “The Mesoamerican Reef.” The Nature Conservancy. nature.org. Reef extent and the four countries it crosses. ↩

12. “After historic 2024 coral bleaching, hope remains for Mesoamerican Reef.” Mongabay, December 2024, on the 2024 Mesoamerican Reef Report Card. news.mongabay.com. Coral cover 19% → 17% (2022–2024) and “the worst bleaching event to date, with approximately 40% of corals affected.” ↩

13. “2023 global heatwave causes mass mortality of a keystone coral on shallow Western Atlantic reefs.” iScience, 2025, doi:10.1016/j.isci.2025.113722. pmc.ncbi.nlm.nih.gov. Puerto Morelos: SST near 35 °C at a +4.8 °C anomaly; August 2023, 57% of Acropora palmata dead and 43% bleached; July 2024, no live A. palmata detected. ↩ ↩²

14. “A Glimmer of Good News from the Mesoamerican Reef.” GCRMN, 8 November 2024. gcrmn.net. First improvement in five years; commercial fish biomass +40%, herbivorous fish biomass +30% since 2022. ↩

15. “Cenote Dos Ojos Tulum: Ultimate Visitor’s Guide.” Tulum Travel Secrets, updated 22 June 2025. tulumtravelsecrets.com. Hours 8 a.m.–5 p.m., water 75–77 °F year-round, guided-tour-only access to the Bat Cave. ↩ ↩²

16. “Snorkeling Sea Turtles in Akumal: Rules, Crowds & How to Book.” Seth Dive Mexico, updated 29 April 2026. sethdive.com. No guided tours on Mondays; daylight hours only. ↩

17. “Yal-Kú Admission.” Yal-Kú Park (official site), checked 8 August 2026. yalkupark.com. Mandatory life jacket, chemical-free sun protection only, open 9 a.m.–5 p.m. daily. ↩

18. “Cancun Sargassum: Where Riviera Maya Beaches Stay Clear.” Deep Arrival, 2026, checked 8 August 2026. deeparrival.com. Cozumel’s leeward west shore and west-facing Playa Norte stay clear in heavy years; Tulum and Akumal most exposed; June–July heaviest. ↩ ↩²

19. “Entrance fees to El Cielo Cozumel.” El Cielo Cozumel Tours, 2026, checked 8 August 2026. blog.elcielocozumeltours.com. Boat-only access by licensed operators, ~1,850-peso standard tour plus 100-peso local tax, mandatory life jackets, 3–5 ft depth at the sandbar, no touching. ↩ ↩²

20. Green, Alison. “Sea of Cortez: Conserving the World’s Aquarium.” The Nature Conservancy, 24 March 2014. blog.nature.org. The Cousteau “aquarium of the world” attribution. ↩

21. “Hidden Baja Undersea Park is the World’s Most Robust Marine Reserve.” Scripps Institution of Oceanography, on Aburto-Oropeza et al., “Large Recovery of Fish Biomass in a No-Take Marine Reserve,” PLOS ONE, 2011. scripps.ucsd.edu. Fish biomass +463% 1999–2009; top-predator biomass up 11-fold. ↩

22. “Riviera Maya Water Temperature.” Seatemperature.net, monthly averages, checked 8 August 2026. seatemperature.net. ↩ ↩²

23. “Sargassum Season: Cancún & Riviera Maya Month-by-Month Guide.” How Is The Sargassum, checked 8 August 2026. howisthesargassum.com. Seasonal shape (May–August arrivals, June–July heaviest, November–March clearest); USF-based 2026 record-year forecast; January and March 2026 early beachings. ↩ ↩²