I don't want this to be a depressing post or anything, but just so ya know, there are some scary studies out there showing how chemical sunscreens wash off our bodies when we swim in the ocean and then trigger a reaction in coral that causes it to bleach out and die. Sunscreen on one person might not seem a like a lot, but when you add up all the peeps worldwide hitting the beach, it comes out to an estimated 4,000 - 6,000 metric tons of sunscreen sliding off swimmers' bodies each year. Yikes!
In all fairness, the studies are rather preliminary and more research is needed before a direct link is established between chemical sunscreen and coral bleaching, but I'm on the side of Better Safe Than Sorry. If switching to an environmentally safe sunscreen means a little less toxic slurry will be swirling through the ocean, then I'm all for it.
If you feel the same way, look for natural sunscreens (no parabens, silicone, or petrochemicals) that use mineral sun filters like titanium dioxide and zinc oxide. I dug around a little and found two that seem to be about as ocean-friendly as you can get: Any sunscreen from Badger and Soleo Organics SPF 30+. I fully plan on taking both of these brands on my upcoming trip to Bora Bora. I don't want to be responsible for trashing paradise!