In earlier times, Ostend was a small village built on the east-end (oost-einde) of an island (originally called Testerep) between the North Sea and a beach lake. Although small, the village rose to the status of “town” around 1265 when the inhabitants were allowed to hold a market and to build a market hall.
The major source of income for the inhabitants was fishing. The North Sea coastline has always been rather unstable and in 1395 the inhabitants decided to build a new Ostend behind large dikes and further away from the always-threatening sea. (from Wikipedia)