The Dead Sea and its shores are 394 m below sea level, making it the lowest elevation on land. It is in fact more a hypersaline lake than a sea since it is landlocked. The dead sea is also one of the saltiest bodies of water in the world. So salty that it is 8 times saltier than the ocean, and harder for people to sink in it.
Another unusual fact is that the Dead Sea discharges black asphalt. It’s unique mineral content has also made it a center of health research. After-all, it was one of the world’s first health center (for Herod the Great).