It was only around the Middle Ages Vlieland became an independent island, before that time it was connected to Texel (the Eierland part). Now the Eierlandse Gat (consisting of the main channels Engelmansgat and Robbengat) forms the separation between the two islands. Vlieland is the second inhabited Wadden Island seen from the west and has the least number of inhabitants after Schiermonnikoog (1138). There is only one village on the Frisian island named Oost-Vlieland. This makes the municipality of Vlieland the second most sparsely populated municipality in the Netherlands. Until the 18th century there were two villages on the island, but the village of West-Vlieland disappeared in the sea in the 18th century due to coastal erosion. The vast nature reserve 'de Vliehors', actually a large beach plain, on the west side of the island serves as a NATO military training area for the air force. Planted forests are located on the east side of the island around the village of Oost-Vlieland. The highest point of all the Wadden Islands together is located on Vlieland and is formed by the Vuurboetsduin (45 meters high) on which there is also a lighthouse. It is not possible to visit the island from Harlingen by car or motorcycle, but the inhabitants themselves are allowed to own a car. Vlieland has a small-scaled environment with two supermarkets, a bakery, a butcher and a harbor shop. Vlieland also has a harbor on the far east side with space for around 300 boats.