The 10 largest seas by surface area are the Philippine Sea, the Coral Sea, the Arabian Sea, the South China Sea, the Weddell Sea, the Caribbean Sea, the Mediterranean Sea, the Tasman Sea, the Bering Sea and the Bay of Bengal. They are ranked from largest to smallest.
There are more than 85 seas in the world. A sea is defined as a body of saltwater that is joined with at least one major ocean, yet is surrounded by a large amount of land. For this reason, geographers often divide seas into two major categories. Seas that are partially enclosed by land are considered marginal seas, while seas that are almost completely surrounded by land are called mediterranean seas.
Although seas are a part of the ocean, they are also home to popular beaches and busy ports. Of the 10 largest seas in the world, the Bay of Bengal is the smallest sea with an area of 2,172,000 square kilometers, yet is considered the largest bay in the world. Likewise, the largest sea, the Philippine Sea, boasts a surface area of 5,177,562 square kilometers. The Philippine Sea is famous for being home to the Mariana Trench, the deepest point in the world.