1. It’s a marketing claim, not a standard
No US agency defines “reef safe”, “reef friendly” or “ocean safe”. A bottle can carry the claim and still contain ingredients that are illegal to sell in Hawaii. The only reliable signal is the Drug Facts panel on the back: the list of active and inactive ingredients.
“Biodegradable” has no definition for sunscreen either. What the biodegradable claim means, and where Mexico requires it →
2. What the science says
Concern started with laboratory studies in the 2000s and 2010s showing that some chemical UV filters — oxybenzone above all — damage coral larvae, trigger bleaching and disrupt the algae corals depend on, with effects stronger in sunlight. Later work found octocrylene accumulates in coral tissue and can break down into benzophenone.
The science is still developing. A 2022 review by the US National Academies concluded that sunscreen chemicals are one stressor among many — warming seas, runoff and disease matter more at global scale — but that the risk at crowded swim sites is real enough to warrant monitoring and more field research. That’s why most laws target the most-studied chemicals rather than all sunscreen.
Sunscreen ingredients to avoid, with the evidence for each →
3. Two kinds of law
Named-ingredient bans list specific chemicals. Hawaii’s statewide law bans oxybenzone and octinoxate; the US Virgin Islands and Guam add octocrylene. Palau’s list also includes some preservatives.
Mineral-only rules go further: the only allowed actives are zinc oxide and titanium dioxide. These apply in Maui County (Maui, Molokaʻi, Lānaʻi), Hawaiʻi County (Big Island) and Palau. A chemical sunscreen that’s legal in Honolulu may not be legal to sell on Maui.
4. How to choose, in four checks
- Actives: zinc oxide and/or titanium dioxide only. This passes every law we track.
- Inactives: for Palau, avoid parabens, phenoxyethanol and triclosan.
- Format: lotions and sticks put less product into the air and sand than aerosol sprays.
- Protection: SPF 30+, broad spectrum, water resistant (40 or 80 minutes). Reapply after swimming — sunscreen doesn’t help the reef or you if it isn’t protecting you.
Or skip the reading: paste any label into the checker, or start from our best reef-safe sunscreens, all of which pass these checks.
5. Beyond sunscreen
The most reef-friendly sunscreen is the one you need less of. UPF rash guards, sun hats and swimming outside midday cut the amount of product entering the water. Rinse off at a shower, not in the lagoon, when you can.
Common questions
Is “reef safe” sunscreen regulated?
No. Neither the US FDA nor the FTC defines “reef safe” or “reef friendly”, so brands can print it on any product. What is regulated is which ingredients specific places ban.
What is the safest sunscreen for coral reefs?
Based on current evidence, a sunscreen whose only active ingredients are non-nano zinc oxide and/or titanium dioxide, with a short inactive list free of parabens and phenoxyethanol. It meets every law we track.
Is mineral sunscreen always reef safe?
It meets every active-ingredient rule, but not necessarily every law: Palau also bans some preservatives, such as parabens and phenoxyethanol, that appear in some mineral formulas. Check the inactive list.
Is an “oxybenzone-free” sunscreen legal in Hawaii?
Under the statewide law, yes, as long as it is also free of octinoxate. Bills to add avobenzone and octocrylene failed in 2021 and 2024. But Maui County and Hawaii County (the Big Island) allow only mineral actives, so most oxybenzone-free chemical sunscreens are still not allowed there.