The official description of a Frisian Island refers to an area with over 0.6 square miles of land rising over the North Sea during high tide. In total, the Frisian Islands cover an area of about 404.4 square miles of the North Sea. The island of Texel is the biggest of the islands, based both on land area as well as population. The islands that make up the Frisian Islands are grouped into three groups; the Dutch Wadden Islands, the German Wadden Islands, and the Danish Wadden Sea Islands. The German Wadden Islands are many of the three island groups and cover a combined area of 173 square miles. The Danish Wadden Sea Islands have the least population of the three island groups, having a total population of about 4,200 inhabitants.
The islands were formed during deglaciation in the earth’s last glacial period, as melting ice sheets triggered the rise in sea levels. Much of the present-day North Sea that was exposed as terrestrial land during the glacial period was submerged as sea levels rose during the start of the Holocene era. Later, tidal action saw sand being deposited as dunes along the seashore. These dunes were 310 miles in length, but powerful waves broke the dunes apart, resulting in the formation of the Wadden Islands and Mudflats. The introduction of plants in the islands stabilized the land that was initially frequently washed away by waves.
Humans have inhabited the islands for thousands of years. The current total population of the habitable islands is estimated to be over 81,000 people. People inhabiting the Frisian Islands are referred to as “Frisians,” named after the German region of “Frisia.” The region around the islands is of great interest in oil exploration, with drilling ongoing near the islands. However, these activities expose the region’s fragile biosphere to significant risks. The area is also a popular route in marine travel, and the increased ship traffic is seen as an environmental hazard by conservationists. There was a controversial plan that aimed at embanking the Friesland mudflat by draining the surrounding Wadden Sea, but these plans attracted great resistance from conservation movements and the plans were subsequently dropped. The countries that lay claim to the islands, Germany, Denmark, and the Netherlands have established a nature reserve that encompasses some of the islands to protect the plant and animals species of the Frisian Islands.
The shape of the islands is frequently altered by violent storms that continuously bombard the archipelago. Some particularly powerful storms struck the ancient Geestland Islands which were broken down to form the North Frisian Islands. A strange movement has been observed on the islands, which are considered to be “migrating” from west to east, whereby the western part of the islands have been disappearing, but the eastern parts appearing to be growing in size. While this “migration” has been slow, its effects are apparent with structures on the islands’ western part (which were initially built on the middle of the islands) gradually being submerged under the sea over hundreds of years.