The Hawaii Sunscreen Ban, Five Years On

Mineral filters are often marketed as the reef-friendlier choice, and many travelers prefer non-nano zinc or titanium. But 'reef-safe' isn't regulated and the research is ongoing, so the most reliable step is reducing total sunscreen in the water with UV-protective clothing and shade.

There's no meaningful regulated difference — both are unregulated marketing terms with no standard US definition. Rather than trust either label, read the ingredient list (many people avoid oxybenzone and octinoxate) and follow the sunscreen laws at your destination.

Research suggests it can. A Stanford-led study in Science found that sea anemones and corals can convert oxybenzone into compounds that turn toxic in sunlight. Several places, including Hawaii, have restricted oxybenzone for this reason, though scientists are still quantifying real-world reef impact.