It’s a well-known fact that the ocean is in critical danger from pollution. The populations of sea creatures are becoming extinct in droves — and much of this is due to coral reef damage.

As of now, over 90% of the Great Barrier Reef is dying. Thirty-five percent is already dead. Gone. Bye.

So what can you do? You’re just one person against the entire ocean. You can’t possibly do anything, right?

Wrong. It’s as simple as switching your sunscreen.

The main ingredient in the majority of sunscreen brands is something called oxybenzone, which is poison to coral and fish. Even some “natural” ingredients like mineral oil are icky for the water. These chemicals cause corals to bleach themselves, expelling the algae that gives them their color and keeps them alive. Corals can sometimes recover from this, but with heated, polluted waters, it’s really difficult to do.

Currently, somewhere between 4,000 and 6,000 tons of sunscreen enters coral reef areas around the world each year, according to the U.S. National Park Service. That’s a lot, considering how little it takes to poison a reef.

The good news is there’s a way around this. There are “reef safe” sunscreens that contain only zinc and titanium oxide as their active ingredient, power UVA blockers that are completely reef safe. You can find them in dive shops or online. Some examples are Stream2Sea, Biodegradable Reef Safe by Tropical Seas, and Coral Safe.

One more thing: imagine how damaging oil spills are to waterways and marine life. Unfortunately, tanning oil does the same kind of damage. In small doses, sure, it’s not going to do much, but when millions of people hit the beaches at once — especially in the summer — it simply rubs off into the ocean while swimming. Definitely best to shower that stuff off before taking a dip.

You still need to wear sunscreen of course. Don’t stop doing that. Skin cancer = not fun. But think twice before jumping into a pool or sea for a swim with skin covered in marine-dangerous chemicals. You could be hurting the world without even knowing it.