Several common ingredients in sunscreens can be harmful to reefs and other sea life, which is why some states and municipalities have banned the sale of sunscreens that use the UV filters oxybenzone and octinoxate. Although no sunscreen has been proven totally safe for aquatic wildlife—wearing a rash guard or other protective clothing while you snorkel is the best choice for coral as well as for your skin—some formulas are friendlier than others. After researching the issue and testing 17 sunscreens that claim to be “reef safe,” we’ve found that Thinksport SPF 50+ Sunscreen has the ingredients scientists recommend in a reef-safe sunscreen, costs less than some of the competition, is widely available, and feels nice on skin.
The main ingredient in Thinksport SPF 50+ Sunscreen is non-nano zinc, the most coral-friendly option available in the US, according to experts. Zinc sunscreen might conjure images of lifeguards with white noses, but this one rubs in among the clearest of those we tested, with minimal effort. Once on skin, it feels less greasy than many sunscreens, and like most mineral sunscreens—which block UV rays with zinc and/or titanium—its smell is more subtle compared with that of most chemical sunscreens. Like the other reef-friendly sunscreens we considered, Thinksport is a lotion, which means that it’s hard to accidentally get excess sunscreen on the sand where it will wash into the ocean, a concern when using sprays. This sunscreen typically costs $4.33 per ounce in the largest-available size; though that’s quadruple the price of our top pick for regular sunscreen, it’s less than the price of many of the other reef-friendly sunscreens we considered.
Why you should trust us
We spoke to two scientists who have researched the effects of sunscreen on sea life, Craig Downs, executive director of the nonprofit Haereticus Environmental Laboratory in Virginia, and Roberto Danovaro, PhD, a marine ecologist at Polytechnic University of Marche in Italy. We drew on research from our main sunscreen guide, for which we spoke to nine dermatologists, a skin cancer educator, and a cosmetic chemist. We also read peer-reviewed papers on how sunscreen affects sea life.
Who this is for
If you’re headed on a reef-themed scuba or snorkel excursion, or even just to a beach in a region that’s home to coral habitats, you’ll lessen your environmental impact by using a sunscreen that skips ingredients known to be harmful to reefs in large quantities. In particular, some sunscreen ingredients can help viruses destroy corals faster, leading to bleaching, according to a 2008 paper published by Roberto Danovaro and colleagues.
The reefs most vulnerable to sunscreen damage are those in highly trafficked areas without a lot of water turnover, like coastal reefs or atolls (circular reef structures left behind after an island sinks), the authors of the paper note.
Some such locations and guided tours may even require reef-safe sunscreen. As reported in The New York Times, both Hawaii and Key West, Florida, voted to ban the sale of sunscreens containing two ingredients found to be harmful to coral: oxybenzone and octinoxate. The laws took effect January 1, 2021. Hawaii's state parks urge beachgoers to forgo certain ingredients, and a chain of hotels in Hawaii provides guests with complimentary reef-safe sunscreen. In Mexico, federal regulation requires use of reef-safe sunscreen in a handful of protected areas. And the nation of Palau became the first country to ban any “reef toxic” sunscreen that contains anyone of 10 prohibited chemicals.
Even if you’re far from reefs, what washes off your body in the ocean (or even the shower) can make its way into the ecosystem, said Craig Downs, executive director of the nonprofit Haereticus Environmental Laboratory, though at that point the ingredients will be far, far more dilute than in the lab studies demonstrating their toxicity to reefs.
More people are choosing to be as cautious as possible and use reef-safe sunscreen all the time, and not just for reef safety. “Reef-safe sunscreen’s main ingredients are zinc oxide and/or titanium dioxide, and they are the only sunscreens the FDA regards as generally ... safe and effective” at this time, said Dr. Lawrence Eichenfield, chief of the pediatric and adolescent dermatology division at Rady Children’s Hospital-San Diego.
However, no sunscreen is foolproof when it comes to sea-life safety. Though good reef-safe sunscreens avoid ingredients that have been clearly demonstrated to cause damage to reefs in large doses, they may still contain trace amounts of the offending substances. Plus, scientists disagree about whether the replacement ingredients are actually safe for sea life. Beyond that, reef-safe sunscreens are generally pricier and harder to rub in than their chemical and combination counterparts, making them potentially trickier to use on a daily basis to best protect your skin from UV rays. And it’s worth noting that chemicals from sunscreen aren’t the main source of worry for reefs—that would be climate change, a phenomenon bolstered by lots of other choices we make every day.
How we picked and tested
There’s no label that denotes a totally reef-safe sunscreen, and it’s unclear if such a thing exists.1 “Reef safer” is probably a better way to describe the options available.
In October 2016, Haereticus Environmental Laboratory executive director Craig Downs set out to create a reef-safe sunscreen label to affix to sunscreens that passed a toxicity test in his lab. But as the applications and samples from companies rolled in, he found that even sunscreens that met the mark in theory contained impurities and unlisted ingredients that have been known to cause damage to reefs. “We’re embarrassed and horrified that no one has passed,” Downs said.
Further, though it’s clear that some sunscreen ingredients do damage to reefs, and it is wise to avoid them while near reefs, there’s no scientific consensus on the best replacements. Downs’s own list, which he calls the “HEL List” is comprised of chemicals backed by varying amounts of data, some of it quite limited. Notably, he and Polytechnic University of Marche’s Robert Danovaro strongly disagree about whether snorkelers should use zinc, a common ingredient. Part of this rift may be that they are operating under different regulations: Europe (where Danovaro is based) has more UV blockers available than the US. “Reef safe” is somewhat of a political term, defined not just by the science, but by what chemicals are approved for general use and available from manufacturers in a given region.
All of this means you can’t reach for any product that’s labeled “reef safe”—an unregulated and unclear definition—and be confident your sunscreen is harmless to the ocean environment. The best thing you can do for corals and skin alike is to cover up with protective clothing as much as possible. Danovaro said he wears a T-shirt while snorkeling.
That said, there are still a few factors to look for in sunscreen to ensure it’s more safe than the competition.
- Minerals: The top one or two ingredients should be non-nano zinc and non-nano titanium dioxide. Particles under a hundred nanometers (in this context, considered “nano”) can be bad news for sea creatures that ingest them, like brine shrimp, and in turn the things that eat the shrimp. (Danovaro is still concerned about non-nano zinc, but in the US it’s the best option we have).
- No oxybenzone: This common UV-stopping ingredient—a key ingredient in our main sunscreen pick—helps viruses damage coral more quickly, as Danovaro identified in his team's 2008 paper on reef bleaching.
- Water resistant: All sunscreens will wash off in water, but the better they are at sticking to your skin, the less of it will wind up in the ocean with the reefs.
- Lotion, not spray: Each time you use a spray sunscreen at the beach, some ends up on the sand, which in turn ends up in the ocean. Most mineral sunscreens are lotions, anyway.
- No parabens: These preservatives are another virus-assisting reef-bleaching culprit. Sunscreens with parabens can be hard to identify, as parabens are often not listed in the ingredients. If a sunscreen advertises aloe or another plant component, it likely contains preservatives needed to keep that plant fresh, Downs told us, so don’t get those formulas if reef-protection is your priority.
- Free of other ingredients that may harm coral: A small slew of chemicals aren’t great for reefs, compiled by Downs in Haereticus’s HEL List. In addition to oxybenzone and parabens, the list includes octinoxate, octocrylene, triclosan, para-aminobenzoic acid (known as PABA), camphor, and microbeads or other small bits of plastic.
Once an FDA-approved sunscreen passed the requirements for being reef safe(r), we considered the following factors:
- SPF: The minimum SPF experts recommend to protect your skin is 30. A bit higher is better, though higher SPF offers diminishing returns in coverage.
- Price: For sunscreen to work well, you need to reapply. A lot. Experts recommend a shot glass worth every two hours, and after you come out of the water. We sought to find a sunscreen that wasn’t a ton of money per application (with reef-safe sunscreens, each application can easily cost upwards of $6).
- Size: Hauling one or two large bottles of sunscreen for a family day at the beach is easier than packing a bunch of small tins.
One thing to not worry about: if a sunscreen is biodegradable. This term is sometimes used interchangeably for “reef safe,” but according to Downs it’s “just a marketing word.” For example, you don’t want your zinc sunscreen particles—which are safe when they are large but harmful when they are smaller—to break down.
We selected more than a dozen sunscreens that fit our requirements (or seemed to: in a testament to how tricky it is to navigate the ingredients, one ended up containing a blocker on Downs’s HEL List). We tested each one for feel and smell, paying close attention to how difficult it was to rub in.