There is honestly a massive amount of pollution in the oceans and that is the responsibility of the human race. Though you did not personally dump toxic waste into the ocean, many other people have, usually under the direction of a company or corporation of some sort. If you dig a little deeper, you will find out that most sunscreens on the market are toxic to coral because they contain certain ingredients. So, in a way, we are all contributing to this problem when we go to the beach. The solution is to use reef safe sunscreen.
Don’t go entirely radical and wear no sunscreen at all. That is also not good because it can lead to serious skin problems and even skin cancer. The use of sunscreen is advised for all people who have exposure to the sun longer than half an hour. Some of these products that claim to be safe for the coral reefs are in fact not. You will discover a great deal of information about this even with just light research. Even the commonly used reef safe formulations that use zinc oxide and titanium dioxide are not safe for the coral, though they are safer for humans than other sunscreens.
You will discover that parabens and many other compounds in common sunscreens can cause serious harm to coral. With the masses of people that go into the ocean waters, this is a huge amount of coral toxic waste. For example, Benzophenone is one ingredient you will find in many brands. It actually damages the coral DNA and this results in coral deformities and mutations while also blocking coral from reproduction. There is no need to get too technical, but you may do so if you want to know more. For the meantime, wear a guaranteed coral friendly sunscreen.