If you refer to the type of sunscreen required by some excursion parks in Mexico (Xcaret, Xel-Ha, etc) or else, you can get it at the mentioned places for reasonable price, they do not try to overprice them. Actually, some give you a sample which is even enough for some skin tipes...
biodegradeable sunscreens are friendly to the coral/fish/sealife.All others can kill it/them.If you have a walmart where you live,they make one called No-Ad.It comes in different strengths and wont hurt the sea enviornment. Dot
I looked EVERYWHERE at home to find biodegradable sunscreen as I didn't want to get ripped off on my vacation. I gave up. THEN I came on vacation (actually am there right now!) and found that BANANA BOAT BOTANICALS, has a sticker on it down here that says "Biodegradable" on it, and it's the EXACT same product I bought at Walmart at home. It's called Banana Boat Botanicals, the one I brought was SPF 15. It's in a green tube and has a very nice scent. Mine didn't have the sticker on it but it looks like the version down here was just stuck on after the fact. But they are the same product so it's ok. Incidentally they charge double down her (Cancun) than they did back home in Canada. Anywhere you buy sunscreen at home should have it. I think there are other SPF levels in this line too.
OK - Finally found some! Hawaiian Tropic SPORT SUNBLOCK SPF 30. Package clearly says "Oil Free, Waterproof, Biodegradable, Environmentally Friendly, PABA free". $9.98 CAD at our local Zellers department store.
According to their website, there is a sunscreen that is biodegradable and eco-friendly, and does not contain chemical sunscreen ingredients - it's called Mexitan, and their website is www.mexitancanada.com, or www.mexitan.com in the U.S.