That's not my opinion. My opinion is that the only study ever done to date on biodegradable sunscreens (Danovaro, 2008) was poorly done and has little application to real-world effects of sunscreen on real-world coral reefs. It's my firm belief that "eco" sunscreens are as helpful to the reefs as SpareAir is to divers, yet both products make their manufacturers lots of money.
I see why dmoore19 posted what he did.
As a scubaboard irregular or maybe I've graduated to semi-regular, I was unaware that this subject had come up before, and apparently been discussed and argued to the point that Bess and Beauty are now a bloody pulps.
I think that there are some things we can reasonably conclude without seeing rigorous scientific proof of said conclusion.
I have looked at the ingredients of many different kinds of sunblock. I think that the ingredients of Mexitan, the brand that I currently have, is more environmentally friendly, and less apt to cause damage to the reef or cenote ecosystems, than "regular" sunscreen.
Even though I am by nature, a cheap SOB, it is a cost that I'm willing to incur, in the (off??) chance that for once I'm doing more good than harm to the environment.
To help with the mental image of me, I do not own a pair of Birkenstocks, or own a Prius. I find both obnoxious.