Beware of products that call themselves reef-safe or reef-friendly; those words have no legal/regulatory/defined meaning. You have to look at the ingredients list. If you see any of following, it is bad stuff. It may be a fine sunscreen for YOU, but not for the reef.
From
Sunscreen 101: Protecting Your Skin and Coral Reefs - Coral Reef Alliance
Key ingredients to avoid are Oxybenzone and Octinoxate. Additionally, look out for Benzophenone-1, Benzophenone-8, OD-PABA, 4-Methylbenzylidene camphor, 3-Benzylidene camphor, and Octocrylene. These can affect corals’ reproductive cycle, damage DNA, and worsen the effects of coral bleaching.
Also, many of these chemicals use different names, possibly to hide what they actually are.