Koh Samui’s Beautiful but Fragile Sea Life
When you think of Koh Samui, you probably picture soft sandy beaches, clear turquoise water, and colorful coral reefs waiting just offshore. Whether you’re swimming at Silver Beach, snorkeling near Koh Taen, or taking a boat to nearby Koh Phangan, sunscreen is one of the first things you’ll pack. But not all sunscreens are safe for the sea. Some of the most common sunscreen ingredients can cause serious harm to coral reefs and marine life. Because of this, the Thai government has introduced strict laws to protect its marine environment. In 2025, these laws are being actively enforced across Thailand, including Koh Samui. Tourists caught using or bringing non-reefsafe sunscreen into protected marine areas can face fines of up to THB 100,000 (around USD 2,700). It’s more important than ever to choose the right kind of sunscreen — both for your skin and for the sea.
Why Regular Sunscreen Damages Coral Reefs
Coral reefs are often called the “rainforests of the sea” because they support such a wide range of life. They provide homes for fish, crabs, turtles, and countless other species. They also help protect coastal areas from erosion and attract travelers from around the world who want to experience Thailand’s natural beauty. Sadly, coral reefs are very sensitive to pollution. When swimmers wear regular sunscreen, some of it washes off into the ocean. Scientists have discovered that several common sunscreen chemicals are toxic to coral even in very small amounts. Two of the worst offenders are oxybenzone and octinoxate. These ingredients can cause coral bleaching, which happens when coral loses its color and becomes weak or even dies. They also damage coral DNA, making it harder for reefs to grow and reproduce. Other ingredients like octocrylene, 4-methylbenzylidene camphor, and parabens have also been shown to harm coral larvae and marine animals. In popular spots like Koh Samui, where thousands of people swim every day, these chemicals can build up in the water and create long-term damage.
The 2025 Reef Protection Law
To fight this problem, Thailand’s Department of National Parks, Wildlife and Plant Conservation first banned certain sunscreens in 2021. However, many visitors didn’t realize how serious the rule was. Now, in 2025, the government is actively enforcing the ban across all marine national parks and key coastal destinations, including Koh Samui. Rangers and marine officials are carrying out checks, and anyone caught using or carrying sunscreen that contains the banned chemicals can face fines of up to THB 100,000. The banned substances include oxybenzone (benzophenone-3), octinoxate (ethylhexyl methoxycinnamate), 4-methylbenzylidene camphor, and butylparaben. The goal isn’t to punish tourists but to protect Thailand’s coral reefs and make sure that future visitors can enjoy the same stunning underwater scenery.
How to Recognize Reef Safe Sunscreen
So how can you tell if your sunscreen is reef safe? The simplest way is to look at the ingredients list. A reef safe or reef friendly sunscreen avoids chemical UV filters and instead uses mineral-based protection. The two safe active ingredients are zinc oxide and titanium dioxide. These minerals sit on top of your skin and reflect UV rays instead of absorbing them. They protect you just as well from the sun but don’t harm coral reefs. When shopping for sunscreen in Koh Samui, look for labels that say non-nano, broad spectrum, and water resistant. “Non-nano” means the mineral particles are large enough that marine life won’t accidentally absorb them. “Broad spectrum” means the sunscreen blocks both UVA and UVB rays. “Water resistant” means it stays on your skin longer, so less of it ends up in the sea. Avoid sunscreens that contain oxybenzone, octinoxate, or other complex chemical filters. Also, steer clear of products with microplastics, parabens, or artificial fragrances, as these can also harm marine ecosystems.
Recommended Reef Safe Sunscreen Brands
If you’re not sure what to buy, here are a few reef safe sunscreen brands that travelers recommend and that are often available in Thailand or online: ThinkSport SPF 50+, Stream2Sea, Raw Elements Eco Formula, Sun Bum Mineral Line, and Banana Boat Simply Protect Reef Friendly. Some local shops on Koh Samui, especially near Chaweng, Lamai, and Bophut, now stock these types of sunscreens because of the government’s campaign to promote reef protection. When shopping, check the label carefully, since some brands sell both safe and unsafe versions.
Tips for Using Sunscreen Responsibly
Even with reef safe sunscreen, there are a few ways to reduce your impact on the environment. Apply sunscreen at least 20 minutes before entering the water so it has time to set. Wear protective clothing like a long-sleeve rash guard, hat, or swim shirt, which reduces how much sunscreen you need to use. Try to stay in the shade during the hottest hours between 10 a.m. and 3 p.m. Rinse off before swimming to remove lotions or sprays that might contain chemicals. And most importantly, share this information with other travelers. Many people simply don’t know that regular sunscreen can harm coral reefs, and a small reminder can make a big difference.
Koh Samui’s Marine Ecosystem and Why It Needs Protection
Koh Samui’s marine environment is part of what makes the island so special. Around the island, you’ll find coral reefs that shelter bright tropical fish and provide feeding grounds for sea turtles. Nearby spots like Koh Taen, Koh Madsum, and the Ang Thong Marine Park are popular for snorkeling and diving. These places are also fragile. Rising sea temperatures, plastic waste, and pollution already threaten their balance. The sunscreen ban is just one part of Thailand’s larger effort to protect its reefs, alongside projects that limit anchor damage, promote coral restoration, and control waste.
Be a Responsible Traveler
As a visitor, you can help simply by choosing a better sunscreen. Every bottle of reef safe sunscreen represents one more step toward a cleaner ocean. It’s an easy, responsible choice that benefits both the environment and the local communities that depend on tourism. So, when you pack for your trip to Koh Samui, take a moment to check your sunscreen. Look for zinc oxide or titanium dioxide on the label, and avoid chemical ingredients like oxybenzone or octinoxate. Remember that in 2025, the Thai government is enforcing its reef protection law, and using unsafe sunscreen could lead to a fine of up to THB 100,000. But more than that, it’s about doing your part to preserve the natural beauty of Koh Samui and its surrounding islands.
Protect Your Skin and the Sea
Choosing reef safe sunscreen means you can enjoy Thailand’s sunshine knowing you’re not harming the very reefs that make this island paradise so magical. Protect your skin, protect the sea, and help keep Koh Samui’s underwater world alive for generations to come.