Thailand sunshine is no joke. One minute you’re happily strolling along the beach, and the next you’re wondering why your shoulders look like they’ve been personally roasted by the sun. So yes, let’s say this nice and clearly from the start: wearing sunscreen is important. But here’s the catch. Some sunscreens, including plenty of common high street options, contain ingredients that may be harmful to coral reefs and marine life. For divers and snorkellers visiting Koh Tao, choosing the right sunscreen is one of those small, easy decisions that can make a real difference. This doesn’t mean you need to spend your holiday hiding indoors like a confused vampire. It just means being a little more thoughtful about what you put on your skin before getting into the ocean. Why Some Sunscreens Can Be Damaging to Coral Reefs Many standard sunscreens use chemical UV filters. These ingredients absorb ultraviolet rays and help stop your skin from burning, which is obviously useful. The problem is that some of these chemicals can wash off into the sea when we swim, snorkel, or dive. Once in the water, certain sunscreen ingredients have been linked to coral stress, coral bleaching, and harm to marine life. Coral reefs are already dealing with rising sea temperatures, pollution, coastal development, and too many careless fin kicks from people who swear they “totally have good buoyancy.” Adding unnecessary chemicals into the mix really doesn’t help. This matters in places like Koh Tao because the reefs are a huge part of what makes the island special. Whether you’re doing your first try dive, completing a course, or heading out to spot blacktip reef sharks, healthy coral means healthier dive sites, more marine life, and better underwater experiences for everyone. For more on travelling and diving with a lighter footprint, have a read of our guide to sustainable tourism in Thailand. Reef-Safe Sunscreen Is Important, But So Is Sun Protection Before we go any further, let’s not throw sunscreen under the dive boat. Protecting your skin is important, especially in Thailand where the sun can be strong even on cloudy days. Sunburn can ruin a dive trip pretty quickly, and nobody wants to spend their holiday waddling around in a T-shirt because their back has turned into a warning sign. The goal isn’t to stop using sunscreen. The goal is to choose better sunscreen and use it in a smarter way. That usually means looking for mineral-based sunscreens that use non-nano zinc oxide or non-nano titanium dioxide as the active ingredient. These sit on top of the skin and physically block UV rays, rather than relying on chemical UV filters that may wash into the water more easily. Be Careful: Not Every “Reef-Safe” Sunscreen Is Actually Reef-Safe Here’s where things get a bit sneaky. Some sunscreen brands use terms like “reef-safe,” “reef-friendly,” “ocean-friendly,” or “marine safe” on the packaging, but those phrases are not always strictly regulated. In other words, a bottle can look wonderfully eco-conscious, covered in blue waves, green leaves, and possibly a happy cartoon turtle, while still containing ingredients you might prefer to avoid. That doesn’t mean every brand is being deliberately misleading. Sometimes definitions vary. Sometimes formulas change. Sometimes marketing gets a little too excited and runs ahead of the ingredient list. Either way, the safest approach is simple: don’t trust the front of the bottle until you’ve checked the back. How to Check Whether a Sunscreen Is Better for Reefs The ingredient list is your best friend here. It may look like someone dropped a chemistry textbook into a font size designed for ants, but it’s worth checking. As a general guide, many divers and reef-conscious travellers choose sunscreens that avoid the following ingredients: Oxybenzone, also listed as benzophenone-3 or BP-3 Octinoxate, also listed as octyl methoxycinnamate Octocrylene Homosalate Octisalate Avobenzone 4-methylbenzylidene camphor, sometimes listed as 4-MBC PABA Triclosan Parabens The two big ones most people talk about are oxybenzone and octinoxate, but if you want to be extra cautious, it’s best to avoid the wider list above and choose a simple mineral sunscreen instead. Look for These Ingredients Instead For a more reef-conscious choice, look for sunscreens where the active ingredient is: Non-nano zinc oxide Non-nano titanium dioxide “Non-nano” matters because very tiny nanoparticles may behave differently in marine environments. Choosing non-nano mineral sunscreen is a simple way to reduce that concern. You can also look for products that are: Water-resistant Fragrance-free or low-fragrance Packaged in plastic-free or lower-waste packaging Clearly labelled with full ingredients Not aerosol sprays Aerosol sprays are best avoided around the ocean because a lot of the product can end up on sand, towels, decks, and eventually in the water. They’re also fantastic at coating everyone downwind, which is not quite the generous holiday gesture people are hoping for. Practical Sun Protection Tips for Divers and Snorkellers Choosing a good sunscreen is only part of the picture. How and when you apply it matters too. Try not to apply sunscreen immediately before jumping into the water. If you put it on right before a dive or snorkel session, a good amount can wash off almost straight away. That’s not great for your skin protection, and it’s not ideal for the reef either. A better approach is to apply sunscreen first thing in the morning, giving it time to settle before you head out on the boat. Then reapply after your dive, especially once you’ve dried off. This gives your skin better coverage while reducing how much product ends up in the ocean. Even better, combine reef-safe sunscreen with physical sun protection. Divers are already pretty good at collecting gear, so what’s one more useful item? Wear a rash vest or long-sleeved UV top Use a hat and sunglasses on the boat Stay in the shade between dives when you can Cover your shoulders during surface intervals Bring a light sarong or cover-up for beach days Physical coverage means you need less sunscreen overall. Less sunscreen on your skin means less sunscreen washing into the water. Nice and simple. What About Divers Wearing Wetsuits? If you’re diving in Koh Tao, you may be wearing a shorty, full wetsuit, rash guard, or just swimwear depending on conditions and personal preference. Whatever you choose, covered skin usually doesn’t need sunscreen. Focus sunscreen on exposed areas like your face, neck, ears, hands, and the backs of your legs if they’re not covered. And yes, ears count. They may be small, but they are surprisingly good at getting sunburned. If you’re not sure what to wear for a trip, our team can help you figure it out before heading to the dive site. You can also contact Phoenix Divers Koh Tao before your visit if you have questions about diving, snorkelling, or what to pack. Reef-Safe Sunscreen Options to Consider Ingredients and formulas can change, so always check the label before buying. Look for non-nano zinc oxide or non-nano titanium dioxide as the active ingredient, and avoid the harmful chemical filters listed above. Here are a few mineral sunscreen brands and products that are commonly chosen by reef-conscious travellers. Before adding one to your basket, give the ingredients list a quick check to make sure the current formula still matches what you’re looking for. Stream2Sea mineral sunscreens Raw Elements mineral sunscreens Badger mineral sunscreens Suntribe mineral sunscreens ReReef You can also read more about sunscreen ingredients and coral reef protection from trusted sources such as the National Oceanic and Atmospheric Administration and the Save the Reef reef-safe sunscreen guide. A Few Quick Sunscreen Shopping Tips When you’re shopping for sunscreen before your Thailand trip, keep it simple. You don’t need to become a marine chemist overnight. Just check the active ingredients, avoid the common chemical filters, and choose a mineral option from a brand that clearly explains what’s inside the bottle. Also, buy before you travel if you can. Reef-conscious sunscreens may not always be easy to find in every shop once you arrive, especially if you’re in a hurry before a boat trip. Nobody wants to start their dive day frantically reading tiny labels while half-asleep and holding a coffee. And remember, the best sun protection plan is a mix of sunscreen, shade, clothing, and common sense. Revolutionary? Not really. Effective? Absolutely. Small Choices Help Protect Koh Tao’s Reefs Using reef-safe sunscreen won’t solve every challenge facing the ocean, but it is an easy step that helps reduce your impact. When more divers, snorkellers, and travellers make better choices, those small decisions add up. Koh Tao’s reefs are home to colourful corals, reef fish, turtles, rays, and sharks. They’re also part of the reason so many people fall in love with diving here in the first place. Choosing better sunscreen is a simple way to show those reefs a little respect while still protecting your skin from the Thai sun. So pack the mineral sunscreen, bring a rash vest, apply it early, reapply after diving, and enjoy the ocean without leaving quite so much behind. Ready to go diving with Phoenix?Planning a dive trip to Koh Tao? Come and explore the island’s reefs with a friendly team that cares about safe diving, good vibes, and protecting the ocean we all love. Contact Phoenix Divers Koh Tao and let’s get you in the water.Get in touch