Isle Of Thanet, an island of England, on the N. coast of Kent, separated from the mainland by branches of the river Stour called the Stour-wantsome, the Mele-stream, and the Nether-gong-wantsome; length 10 m., breadth 5 m.; area, about 40 sq. m.; pop. in 1871, 30,134. The most important towns are the watering places Ramsgate, Margate, and Broadstairs. The N. E. point of the island is called the North Foreland, and has a lighthouse. The surface, elevated and nearly level, is cultivated with great care. In the time of the Romans the channel on the N. W. side, now almost closed, was from 1½ to 4 m. wide, and was used as the main passage for vessels going toward London; and it continued to be navigable for vessels of considerable size till the time of the Norman conquest. The island was then nearly circular, but it is now an irregular oval. The washing away is still going on, and the average annual loss is estimated at 2 ft. on the N. side, and 3 ft. on the S. side between Ramsgate and Pegwell bay.