The West Frisian Islands and the Houtribdijk, Holland – February 2nd, 2009
The West Frisian Islands are a chain of islands in the North Sea off the Dutch coast. The islands visible here belong to Holland (the Netherlands); however, the chain continues further east as the German East Frisian Islands.
From west to east the islands are: Noorderhaaks, Texel, Vlieland, Richel, Griend, Terschelling, Ameland, Rif, Engelsmanplaat and Schiermonnikoog. The ones obscured by clouds, continuing to the East, are: Simonszand, Rottumerplaat, Rottumeroog and Zuiderduintjes.
The Frisian Islands are nowadays mostly famous as a holiday destination. Ferries allow tourists and residents to move from island to island.
Below the islands is what was formerly known as the Zuiderzee, a shallow inlet of the North Sea in the northwest of the Netherlands.
In the 20th century, however, the majority of the Zuiderzee was closed off from the North Sea (leaving the mouth of the inlet to become part of the Wadden Sea) and the salt water inlet changed into a fresh water lake called the IJsselmeer.
The water in the inlet contains a dark green algal bloom that appears more intense in the souther section. This is because the lower part is actually a shallow lake called the Markermeer.
The Markermeer and the IJsselmeer are separated by a dike called the Houtribdijk. It is 30 kilometers long and connects the cities of Lelystad and Enkhuizen. The structure itself is not visible in the image, but it’s precise location can be identified as the line where the algae changes from bright green to dark greenish-black.