Recently it was announced that Maya Bay in Thailand, the piece of paradise made famous by the 2000 Leonardo DiCaprio film The Beach is to be closed indefinitely.

You could blame this on the damage done to the ecology of the beach by the 6,000 tourists who have visited it daily over the past 18 years. You could also blame another culprit.

According to local tour operators, many of those tourists pee in the sea and, together with the urine that boats dump into the bay from their toilets, this is causing damage to the coral and other marine life in the vicinity.

However, while research has shown peeing in smaller, contained, bodies of water, such as swimming pools, is potentially hazardous to the health of the water and fellow swimmers, when it comes to large bodies of water, such as the ocean, it’s not necessarily the case.

Urine is 95% water but does contain other things, among them sodium, chloride, waste products, like urea, and trace amounts of the things we put into our bodies, such as antibiotics and contraceptive pills, as well as small amounts of bacteria.

In a body of water like the Atlantic Ocean, which contains around 350 quintillion litres of water, the addition of urine doesn’t have much of an impact as most of the waste materials in our pee are instantly diluted.

The American Chemical Society recently posited that even if every person on Earth were to pee in the sea at the same time the amount of urea produced would only equal 60 parts per trillion. That might be comforting to those of us too lazy to make it to the nearest public bathroom when the urge comes on during a pleasant splash in the ocean but there are exceptions where peeing in the sea might have a negative effect on marine life.

In smaller or protected bodies of water, a large influx of urine can cause the overgrowth of seaweed and algae, which can be detrimental. Excess nitrogen, which is contained in urea, can also destroy coral reefs in places where water is not flushed or has a low rate of exchange of new water.

It has also been found that hormones contained in birth-control pills and replacement therapies can change the behaviour of sea life, such as fish, and impact on their growth and reproductive abilities. 

Don’t even think of doing a number two – faeces is not good for anyone or anything in the sea as it contains gut bacteria that are directly linked to diseases in coral.

The moral of the story for sea lovers and DiCaprio fans alike is that if you’re enjoying yourself in a gentle, coral-filled body of idyllic but still ocean, hold it in until you reach the nearest loo – for the good of the ocean and its millions of dwellers.

This article was first published by the Sunday Times