Reef-Safe Sunscreen Rules

If you dive or snorkel in Hawaiʻi, sunscreen is part of your gear, and the islands have some of the strictest sunscreen rules in the world. The goal is to cut the amount of certain UV-filter chemicals that wash off swimmers' skin onto nearshore reefs, where research has linked some of them to harm in corals and other marine life. The rules are not identical across the state, so it helps to know which applies where you are staying and diving.

This page is about the rules themselves. For the dive habits that protect coral, such as buoyancy, streamlining and not touching anything, see our companion article on reef-safe diving.

Layer 1: The Statewide Ban (Act 104)

In 2018 Hawaiʻi became the first U.S. state to pass a law aimed at sunscreen ingredients for the sake of its reefs. Act 104 took effect on January 1, 2021. It prohibits the sale and distribution in Hawaiʻi of over-the-counter sunscreens containing oxybenzone or octinoxate without a prescription from a licensed health-care provider.

Two details matter for visitors. First, it is a rule about selling and distributing, not about wearing. Nobody on Waikīkī Beach is checking the bottle in your bag. Second, it covers only those two chemicals. Many chemical sunscreens use other filters and remain legal to sell under the state law. A 2022 bill that would have added avobenzone and octocrylene to the statewide ban did not pass.

Layer 2: Maui County's Mineral-Only Rule

Maui County, which includes Maui, Molokaʻi and Lānaʻi, went much further. Ordinance 5306, which began as Bill 135 and was signed in December 2021, has been in force since October 1, 2022. It bans the sale, distribution and use of non-mineral sunscreens without a prescription. Only sunscreens whose active ingredients are zinc oxide and/or titanium dioxide are allowed. Violations are treated as violations of the county code, with fines going to a county environmental fund.

For divers this is the rule that matters most, because so much of Hawaiʻi's best-known diving happens in Maui County waters: Molokini, the Lānaʻi Cathedrals, Mākena and the West Maui reefs. Pack mineral sunscreen if your trip includes any of them.

Layer 3: Hawaiʻi County's Mineral-Only Sales Ban

On Hawaiʻi Island, the County Council passed Bill 167 in 2022. It became Ordinance 22-81 without the mayor's signature in July 2022, and the ban took effect on December 1, 2022. It prohibits selling and distributing sunscreens with active ingredients other than zinc oxide or titanium dioxide, unless prescribed, with fines of up to $1,000 for violations. As reported, the ordinance targets sales and distribution rather than personal use, but a mineral sunscreen is the only kind you will be able to buy on the island anyway.

What About Oʻahu and Kauaʻi?

The statewide Act 104 ban applies on every island, including Oʻahu and Kauaʻi. During our most recent review we did not find a county-wide mineral-only ordinance for the City and County of Honolulu or for Kauaʻi County. Laws change, though, and individual parks or tour operators may set their own requirements. Many dive and snorkel boats statewide already ask guests to use mineral sunscreen only, regardless of the county rule.

Unless you have a prescription for a specific product, one choice satisfies every rule above: a sunscreen whose active ingredients are only zinc oxide and/or titanium dioxide.

How to Read the Label in Ten Seconds

Ignore the front of the bottle. Words such as "reef-safe," "reef-friendly" and "ocean-safe" have no single legal definition, and some products that carry them still contain chemical filters. Turn the bottle over to the Drug Facts panel and look at Active ingredients.

• Only zinc oxide and/or titanium dioxide listed? Compliant everywhere in Hawaiʻi.
• Oxybenzone or octinoxate listed? Cannot be sold anywhere in the state without a prescription.
• Avobenzone, octocrylene, homosalate, octisalate or similar listed? Not mineral, so not allowed in Maui County and not for sale on Hawaiʻi Island.

Inactive ingredients are not what these laws regulate, but many reef-focused divers also prefer lotions to aerosol sprays, which drift onto sand and boat decks.

A Diver's Approach: Cover First, Then Coat

The less sunscreen you use, the less ends up in the water, and divers have an advantage here: most of the body is already covered by a wetsuit or dive skin. A practical routine looks like this:

1. Wear a full-length suit or rash guard and leggings for snorkeling and surface intervals.
2. Apply mineral sunscreen to exposed skin such as the face, ears, neck and backs of the hands, ideally 15 to 20 minutes before you get in so it sets.
3. Keep it off your mask skirt. Sunscreen on the inside of a mask stings and fogs. Apply around the eyes carefully, or use a hat and shade on the boat instead.
4. Reapply on the boat between dives rather than in the water.
5. Use a hat and UPF clothing for long surface intervals and boat rides.

Why These Rules Exist

Hawaiʻi's nearshore reefs face many pressures, including warming ocean temperatures, land-based runoff, sediment and heavy visitor use at popular bays. Lawmakers cited research suggesting that certain UV filters can harm corals and other marine organisms as one reason to act on the factor visitors control most directly. Scientists continue to debate how large the sunscreen effect is compared with other stresses. For a diver the practical answer is the same either way: mineral sunscreen and good coverage cost little, and they remove one avoidable pressure from the reefs you came to see.

One bottle, every island: if the active ingredients are only zinc oxide or titanium dioxide, you are covered everywhere in Hawaiʻi.