We believe Maui, Hawaii is the only location that outright prohibits the sale of toxic sunscreen. Your safest bet is to look for mineral based solutions.

https://savethereef.org/about-reef-save-sunscreen.html

In a nutshell: The ONLY active ingredients in sunscreen that are safe for the reefs are non-nano zinc oxide, and titanium dioxide. 

Here are some of the ingredients in common sunscreens today that are harmful and toxic:

• Oxybenzone
• Octinozate
• Octinoxate
• Avobenzone
• Retinyl Palmitate
• Homosalate
• Octocrylene

More:

The Best Sunscreen for Surfers – (That’s Reef Safe)

The two chemicals that have been banned by the state of Hawaii are oxybenzone and octinoxate (see HRS § 342D-21). Maui County goes further and bans all non-mineral sunscreens (see MCC § 20.42.010), but that doesn’t apply on Oʻahu.

Check the label to see what active ingredients are listed. None of these should include oxybenzone or octinoxate per state law.

If you want a 100% reef-safe sunscreen, you’ll want a mineral sunscreen, which means the active ingredients will be either titanium dioxide, zinc oxide, or both.