Tiengemeten used to be about five hectares in size. But due to siltation and reclamation this sandbank in the Haringvliet grew into a real island. In 2006 the island was returned to nature. A hole was made in the dike in the south, so that a large part of the island is now under the daily influence of the river. Similarly, the island offers grasslands, mud flats, swamp and forest.

Tiengemeten gets its name from the “gemet,” an old surface measure, about half a hectare. This island originated around 1600 as a small sandbar of about 10 “gemet” (= Tiengemeten in Dutch).

Since 1997 Tiengemeten is owned and managed by Natuurmonumenten (a Dutch society for preservation of nature monuments).