Four great intercontinental enclosed seas are included between adjacent continents - the Arctic Sea, the Central American or West Indian Sea, the Australo-Asiatic or Malay Sea and the Mediterranean Sea.
Telegraphs.-The inception of the Persian Gulf telegraphs, which formed the first links in an intercontinental chain, was dictated not by local interests, but by broad considerations of national advantage.
The Mediterranean Sea, the best-known member of the intercontinental class, is separated from the Atlantic Ocean by a ridge running from Cape Spartel to Cape Trafalgar on which the greatest depth is only 175 fathoms. The depth increases so rapidly towards the east that soundings exceeding 500 fathoms occur off Gibraltar.
The greatest of the intercontinental seas, the Arctic, comes nearest to oceanic conditions in the extent and depth of its depressions.