The Mediterranean Sea was once part of an ancient ocean called the Tethys Ocean. Around 5.9 million years ago, the sea became isolated from the Atlantic Ocean during a period known as the Messinian Salinity Crisis, leading to its saltier composition.
Around 5.9 million years ago, the sea became isolated from the Atlantic Ocean during a period known as the Messinian Salinity Crisis, leading to its saltier composition. 
