What to wear snorkeling: sun, stings and staying warm

What you wear snorkeling does three jobs. It keeps the sun off you while you float face-down for an hour with your back at the surface. It keeps you warm enough to stay in long enough to see anything. And it decides, more than most people realize, whether you come out with a rash.

Almost everything else is optional. What follows is what earns its place — plus one piece of standard advice that is wrong often enough to be worth correcting.

Start here

• Warm clear water, half a day off a boat. Swimsuit, a long-sleeved top with a UPF rating, mineral sunscreen on the rest. Nothing else is required.
• A full day in strong sun. The same, plus something over your legs and something on your head.
• Cooler water, or you feel the cold. Add a shorty or a thin full suit.
• May or June, anywhere from Florida round to the Caribbean. Read the section on stings first. It changes what you wear and what you do the moment you get out.

Sun is the hazard you will actually meet

A snorkeler is a uniquely bad case for sun exposure. You are horizontal and motionless, the water holds you at a constant temperature so you never feel hot, and the parts pointed at the sun — the backs of the legs, the lower back, the neck and the ears — are the parts you cannot see and did not think about. The fix is fabric rather than lotion, because fabric does not wash off or wear out over an hour.

The number to look for is a UPF rating. UPF 50 fabric blocks 98 percent of ultraviolet, and anything measured above 50 is labeled “50+” because the standard caps the reportable figure there.¹²

Which brings us to the shirt most people actually pack. A plain white cotton t-shirt rates about UPF 7 dry, and UPF 3 once it is wet.¹ Three means a third of the UV is reaching skin you covered specifically so it would not — and the shirt is never going to dry out.

A rated long-sleeved rash guard is the straightforward answer, snug rather than loose — O’Neill’s Basic Skins long-sleeve or the Hurley women’s version are the plain forms of it. For a full day, UPF 50+ swim leggings cover the backs of the legs, which is where guests on our tours get caught out more than anywhere else.

The rash guard problem nobody mentions

Here is where the standard advice goes wrong. Almost every guide to this recommends a long-sleeved rash guard partly as protection against jellyfish stings. For the commonest sting problem in the water most readers of this page will be swimming in, that is backwards.

Seabather’s eruption is caused by the larvae of the thimble jellyfish, Linuche unguiculata, and of the sea anemone Edwardsiella lineata. They are small enough to pass through fabric, and once through they are trapped against your skin, where pressure sets off the stinging cells. Divers Alert Network puts it plainly: the larvae “can find their way into bathing suits — even passing through the mesh of some suits — where they become trapped against the skin”.³ The clinical literature adds that lesions concentrate at pressure points such as the waistband, and that loose or porous clothing holds more larvae than tight, smooth fabric.⁴

So a baggy t-shirt or a loose rash guard is not a barrier. It is a net.

Timing and place narrow this a long way. It is a southeastern United States, Gulf of Mexico and Caribbean phenomenon, and it peaks in May and June.⁴ Outside that window it is not worth planning around. Inside it, wear something tight-fitting and smooth rather than a loose shirt, rinse yourself and your kit as soon as the suit is off, and treat the rash guard as a sun garment rather than a sting garment.

Sunscreen: read the panel, not the label

Whatever the fabric does not cover needs sunscreen, and this is the item where the marketing is least reliable.

“Reef safe” and “reef friendly” are claims on a front label. The National Park Service is unusually direct about what they are worth: sunscreens carrying them “may still include ingredients that can harm corals”, and the advice is to “always look at the label and select sunscreens with only zinc oxide or titanium dioxide”.⁵ NOAA lists ten sunscreen chemicals of concern and notes that mineral sunscreen “is considered a better option because there are less effects to aquatic organisms”.⁶

Regulation points the same way, and it names chemicals rather than labels. When the FDA reviewed the sixteen filters on the US market in 2019, only zinc oxide and titanium dioxide were proposed as generally recognized as safe and effective; twelve others, including oxybenzone, octinoxate and octocrylene, went into an insufficient-data category.⁷ Hawaii’s Act 104 has prohibited the sale of sunscreen containing oxybenzone or octinoxate since 1 January 2021,⁸ the US Virgin Islands added octocrylene from 30 March 2020,⁹ and Palau’s ban preceded both.¹⁰

One that passes on the only test that matters is Blue Lizard Sensitive SPF 50: zinc oxide 10 percent and titanium dioxide 8 percent, and no other UV filter in it at all.¹¹ That is the whole specification above, in a bottle you can buy without reading a label in a shop, and it is legal everywhere on the list in the paragraph before this one.

Whatever you end up with, the ten-second check is still worth knowing, because a manufacturer can reformulate under the same product listing and the front of the bottle will not tell you: turn it over and read the active ingredients. Only zinc oxide, only titanium dioxide, or both, and you are fine. Anything else and you are not.

Apply it at least fifteen minutes before you get in rather than on the swim platform, and put it on before the rash guard does, because the strip of skin the neckline exposes when you stretch out flat is the one that burns.

Swimwear that stays where you put it

This is the part I have watched go wrong most often, and none of it is about the sun.

String ties come undone. Between a mask strap, a vest crotch strap and an hour of small waves, a bikini tied at the neck or the hip will eventually work loose, and it always happens at the furthest point from the boat. A swimsuit that fastens rather than ties removes the problem. Anything with a skirt is the wrong garment: the fabric floats up in front of you and obscures the only view you came for.

Fitted boardshorts with a proper drawstring work for most men and, layered over swim bottoms, for a lot of women too. They cover the tops of the thighs and stop swim bottoms riding up under a vest strap.

Whatever you pick, you should be able to forget about it. Anyone spending the swim adjusting their swimsuit is not looking at the reef.

Warm enough to stay in

Snorkelers get cold in water that divers find comfortable, and the reason is not the temperature.

A diver is finning, working and moving through the water. A snorkeler floats on the surface almost motionless, often for an hour, with the whole back of the body exposed to the air. On our tours the water temperature is rarely what ends a swim early. What ends it is somebody who got in feeling fine, stopped moving, and was quietly losing heat for forty minutes before they noticed.

There is no honest universal chart for this, because it depends on the person more than on the water:

• Genuinely warm tropical water, and you are not cold-prone. You need nothing. The rash guard you are already wearing for the sun adds a little warmth for free.
• Warm water, but you are the one who is always cold. A shorty, or a thin full suit. It costs nothing in mobility and it turns a thirty-minute swim into an hour.
• Anything you would call bracing on entry. A full suit, and neoprene socks and gloves before extra thickness elsewhere, because hands and feet go first.

If you have been cold on a swim before, you will be cold on this one. Bring the layer.

Feet

Fins cause blisters, and they do it at the heel, on the second half of the swim, when it is too late. Neoprene socks stop the rub and keep your feet warm for the same motionless-on-the-surface reason as above. Buy them before the fins if you can, or try them on with the fins if you already own them: a sock takes up room in the foot pocket, and a fin that fitted bare can be tight over 3mm of neoprene.

If the entry is off rocks rather than a boat ladder, or anywhere with sea urchins, a sock is not enough and you want a soled boot. Anti-slip neoprene boots go under fins and let you walk in over anything sharp. Urchin spines through a bare foot is the most common injury I see, and it is entirely preventable with a five-minute decision on the beach. If you have skipped fins altogether, wear the boots anyway — getting in and out is the part of snorkeling that hurts people.

Head and hair

If your hair is thin or you have none, your scalp is pointed at the sun for the whole swim and it will burn. A breathable, fast-drying neck gaiter or headwear tube handles it, sits under a mask strap without interfering, and doubles as neck cover on the boat.

If your hair is long, tie it back before the mask goes on: a single strand across the sealing surface will let water track in for the whole swim. Bring spare ties — the item most often lost overboard and the one nobody thinks to pack twice.

Color, and the question people are really asking

People search for what colors not to wear snorkeling, and what they are usually asking about is sharks. The honest answer is duller than the folklore. The International Shark Attack File notes that “most sharks are colorblind, and yellow is likely not as attractive as once popularly believed”, and that what they do register well is contrast.¹² The “yum yum yellow” rule people repeat is at best an approximation of a contrast effect, not a color effect.

Set against that is a risk you are enormously more likely to meet, which is a boat that does not see you. Bright gear is what makes a snorkeler visible from a wheelhouse, and the Attack File’s own judgement is that this benefit “far outweighs the minimal risk of attracting a shark”.¹² Wear the bright thing.

The one concrete piece of advice here is not about clothing at all. Leave jewellery on the boat: “the glint of light reflecting off metal approximates the glint of light off the scales of fishes, the normal food items of most sharks”.¹² It is also how watches and rings get lost.

Valuables

Leaving a phone and a wallet on a towel is the risk of the day on a public beach. A phone pouch rated IPX8 on a waist strap goes in with you, and you can still use the camera through the window. For anything larger, our guide to waterproof bags for snorkeling covers the options.

The gear you wear, briefly

Four things go on your body that are not clothing, and each has its own page here, so this is deliberately short.

Mask. The one thing worth owning rather than borrowing, because fit is personal and a leaking mask ruins a swim more reliably than anything else. If you wear glasses, see how to snorkel with glasses. A new mask needs the manufacturing film scrubbed off the lens before first use or it will fog whatever else you do — the method is in cleaning and preparing snorkeling gear.

Snorkel. A comfortable silicone mouthpiece matters more than any other feature, because jaw fatigue is what makes people get out. Beginners do better with a dry snorkel, which shuts when it goes under.

Fins. Genuinely optional, and the most awkward thing to pack, so renting on arrival is a perfectly good answer. If you are buying, we compare sets in travel snorkel gear.

Vest. Most operators hand one out and most people should wear it; it is the only item here that is a safety device rather than a comfort. Which vest, and whether a given one counts as real flotation, is a separate question we answer in full.

What the boat gives you, and what it does not

At a minimum a tour provides a mask and a snorkel. Most also provide fins and a vest, and operators in cooler water provide wetsuits. What almost none of them provide is anything above the gear section on this page — sun protection, clothing, footwear and sunscreen are yours.

Rental gear is usually serviceable and occasionally not, and the failure is almost always fit: a mask that sealed on the person before you and does not seal on you. Put it on dry, without the strap, and inhale gently through your nose — it should hold itself on your face. Ask what else is provided, too, because half the arguments about packing disappear once you know whether wetsuits are on board. For one trip a year, renting is the sensible answer, and we would rather say so than sell you fins you will use once.

The list

• Swimsuit that fastens rather than ties
• Long-sleeved top with a UPF rating, snug rather than loose
• UPF leggings or boardshorts if it is a full day
• Mineral sunscreen — zinc oxide or titanium dioxide only, checked on the back of the bottle
• Neoprene socks, or soled boots for a rocky or urchin-prone entry
• Something for your scalp, and spare hair ties
• A thin suit or shorty if you have ever been cold on a swim
• Waterproof pouch, and a dry layer for the ride back
• No jewellery

Frequently asked questions

Frequently asked questions

What is the best thing to wear snorkeling?+

A swimsuit that stays put, a long-sleeved top with a UPF rating over it, and mineral sunscreen on whatever is still showing. Everything else — a wetsuit, neoprene socks, something on your head — depends on the water temperature and how long you plan to be in.

What colors should you not wear snorkeling?+

The shark question behind this one has a duller answer than the folklore suggests. The International Shark Attack File notes that most sharks are colorblind and that yellow is not the draw it was once thought to be; what they register well is contrast. The practical advice runs the other way, because bright, high-contrast clothing makes you easier for a boat to spot, and that is the risk you are far more likely to meet. Leave shiny jewelry on the boat, though — the Attack File is specific that the glint off metal resembles the glint off fish scales.

Do you need a wetsuit for snorkeling?+

Usually not in the tropics, and more often than people expect everywhere else. A snorkeler floats almost motionless on the surface for an hour, which loses heat far faster than swimming or finning does, so water that felt fine on entry can end the swim thirty minutes early. If you are cold-prone, a thin top or a shorty buys you the rest of the hour.

Can you wear a bikini snorkeling?+

Yes, if it is one that stays on. Avoid string ties, which work loose against a mask strap, a vest crotch strap or an hour of small waves, and avoid anything with a skirt, which floats up and blocks your view of what you came to look at. Many people layer boardshorts over swim bottoms, which also covers the part of you the sun reaches most.

What do you wear under a wetsuit for snorkeling?+

A swimsuit, and preferably a smooth, close-fitting one. Loose or textured fabric under neoprene chafes at the shoulders and behind the knees, and in seabather's eruption season it gives larvae somewhere to lodge. Nothing more technical than that is needed for surface snorkeling.

What should I wear on a snorkeling boat tour?+

Wear your swimsuit under your clothes so you are not queuing for a changing cubicle, bring a long-sleeved top and a hat for the deck, and bring a dry layer for the ride back, which is colder and windier than the ride out. Sunscreen goes on at least fifteen minutes before you board, not on the swim platform.

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References

Footnotes

1. “Sun-Protective Clothing.” Skin Cancer Foundation, reviewed by Elisabeth G. Richard, MD, skincancer.org. ↩ ↩²

2. “D6603 Standard Guide for Labeling of UV-Protective Textiles.” ASTM International, store.astm.org. ↩

3. “Seabather’s Eruption.” Divers Alert Network, dan.org. ↩ ↩²

4. “Seabather’s Eruption.” StatPearls, National Center for Biotechnology Information, ncbi.nlm.nih.gov. ↩ ↩² ↩³

5. “Protect Yourself, Protect the Reef! The Impacts of Sunscreens on Our Coral Reefs.” U.S. National Park Service, nps.gov. ↩

6. “Skincare Chemicals and Coral Reefs.” National Ocean Service, NOAA, oceanservice.noaa.gov. ↩

7. “Sunscreen Drug Products for Over-the-Counter Human Use.” Proposed rule, Federal Register, U.S. Food and Drug Administration, 26 February 2019, federalregister.gov. ↩

8. “Hawaii Governor Signs Law Banning Chemicals from Sunscreen Products.” Hunton Andrews Kurth, on Hawaii SB 2571 / Act 104 (2018), hunton.com. ↩

9. Act No. 8185, Bill No. 33-0043, Thirty-Third Legislature of the Virgin Islands, dc79r36mj3c9w.cloudfront.net. ↩

10. “Palau is first country to ban ‘reef toxic’ sun cream.” BBC News, 1 January 2020, bbc.com. ↩

11. Drug facts for Blue Lizard Sensitive Mineral Sunscreen Lotion SPF 50+: active ingredients zinc oxide 10%, titanium dioxide 8%, and no other UV filter. Read 31 July 2026 on incidecoder.com, which reproduces the label, and corroborated against the manufacturer’s own listing at bluelizardsunscreen.com. Check the panel on the bottle you actually buy — a listing can be reformulated without changing. ↩

12. “Apparel Color.” International Shark Attack File, Florida Museum of Natural History, floridamuseum.ufl.edu. ↩ ↩² ↩³