Administratively it is a municipality in the Nordwestmecklenburg district, consisting of Kirchdorf, the main settlement, and the smaller Timmendorf, Fährdorf, Kaltenhof, Vorwerk and Gollwitz. It covers an area of 36.02 km² and has 2873 citizens. Satellite views show that most of it is used as farmlands. With its fine beaches and sheltered harbors, it is a popular recreational destination. At Timmendorf harbour there are a pilot's station and facilities for yachts and local fishermen; Kirchdorf has a yachting harbour and a boatyard. Wismar Bay is cited by the 1911 Encyclopedia Brittanica as the finest harbor on the Baltic.
The name of the island derives from the Germanic light god Phol, better known as Baldur. In 1612 Adolf Friedrich I of Mecklenburg-Strelitz started the construction of a fortress on the island, making use of the strategically good location. In 1619 it was completed, but it proved not secure enough, as during the Thirty Years' War in 1631 the Swedish occupied it. In 1903 it was returned to Mecklenburg from Sweden. Since 1927 the island has been connected to the mainland by a causeway.
Nearby Walfisch island was also fortified.