If you have ever gone scuba diving, your ears start to feel like they’re going to burst once you reach a depth of 20 meters. Go down for a while longer and your lungs will collapse, instantly killing you. So how do some fish travel to depths of 8,200 meters (a staggering 10 times the height of the Burj Khalifa)? The answer to their miraculous survival may lie in a smelly chemical named trimethylamine N-oxide (TMAO).

Pressures at these deep depths are similar to 1,600 elephants standing on your head. Because of this tremendous pressure, water molecules get shoved against proteins such as lactate dehydrogenase, a protein essential for energy production. This shatters the important proteins and leads to the inability to repair and create new cells, resulting in death. TMAO changes all of this. It bonds with and stabilizes the water molecules, keeping the proteins from being damaged. The further down you go, the more TMAO you need to stay alive—so the deepest sea creatures have the highest levels of this fascinating chemical.

TMAO also happens to be the reason why fish get stinkier after being out of water for a while. When they are not swimming, the fish have less TMAO and more trimethylamine (TMA), a more pungent substance that is responsible for the “fishy” smell. TMA continuously turns into TMAO in the presence of water, so when the fish is out of the water, the reaction stops, and the TMA remains unchanged.

TMAO is already being used in the medical field to treat diseases caused by high pressure, such as glaucoma (high pressure in the eye) and cystic fibrosis (high lung pressure). Recent research has also shown that TMAO may have helped prevent death in rats with heart failure. All in all, TMAO injections are a possible treatment—although you may walk around smelling like a rotting fish for a little while.