"middle" is very arbitrary
If you use the currently defined Prime Meridian as the starting point then the "middle" could be at 180° - - - which runs mostly through the Pacific Ocean.
If you are looking down on the North Pole, then the Arctic Ocean is in the middle.
If you run around the equator, then the Atlantic, Pacific, and Indian oceans lie in the middle.
If you consider the middle to be the center of the Earth, then I don't think you could consider what occupies that space as a "sea". We believe the center of the Earth is solid.
the Mediterranean sea
the Atlantic sea
Mediterranean Sea
Mediterranean Sea
terra
Ask the sea in the middle of the earth
Mediterranean Sea
A Pleasure Beach has no beach, just lots of amusements and fair ground rides.
it is located in the middle of the earth.
middle of the earth
The most western sea is the Sundering Seas (aka Belegaer or The Great Sea) that separated Middle-earth from Valinor.
Some places on Earth that are located below sea level include the Dead Sea, the Danakil Depression in Ethiopia, and the Salton Sea in California.