Associate professor of biology at Temple University Erik Cordes has been studying this "lake" at the bottom of the Gulf of Mexico. The water in this "lake within the sea" is about five times as salty as the sea water and contains highly toxic methane and hydrogen sulfide. It cannot mix with the sea water forming a "lake".

You can see in the video above that some crabs and other sea life died as a result of getting into the brine pool. Only bacteria, tube worms and shrimp can survive.

The scientists had to be super careful as they got in close to not damage the wall around the "lake" because it would cause the brine pool collapse.

Scientists can also use this area as a possible example of environments on other planets. Watch the video of scientists exploring the area in a submarine below.

This is absolutely fascinating to watch.