Any sunscreen you buy should contain at least 5% zinc or titanium dioxide, be over 30SPF, and say "waterproof")
For the body we recommend HIC 2X sunblock, Alligator, Hawaiian Blend Sport with Zinc, or La Roche-Posay Helioblock S Athelios 40 (not 60 SPF).
For additional face block (for swimming/surfing) we recommend Vertra, Shiseido Sun Protection Skin Foundation SPF 35, HIC 2X sunblock, Zinka Nosecoat, Headhunter Surf Screen, and UV Natural Sport.
We do not recommend Coppertone, Bullfrog, or most Banana Boat products.
Old sunscreens can separate and burn your skin, so get a new good tube for your trip. While buying sunscreens remember that SPF 70 can be the same as SPF 30 and is really a marketing scam. What is most important is that what sunscreen you apply sticks to your skin the longest. If it's great protection but washes off with your first wave, it doesn't help. The face sunscreens we recommend above stay on after at least two hours in the water and will not run into your eyes.
Remember to apply sunscreen at least 30 minutes before getting wet or sweating to allow the sunscreen to bond with your skin.