Floating islands in Norway. While bizarre, the phenomenon of floating islands is fairly common around the world. Composed of aquatic plants, mud, and other detritus, they’re generally capable of supporting not only a varied aquatic community below, but also small trees and species above. They tend to form when plants like cattails or reeds extend out into deeper water and are torn loose from shore by storms. Some have been known to last only a season, while others endure for decades or longer. (Source)