The Mývatn area has unique geological and biological conservation values. Precipitation is trapped by the porous volcanic bedrock and moves beneath the surface until it reappears in a series of springs which supply systems of rivers and lakes. The largest of these is the wetland area of Mývatn and Laxá.Mývatn and Laxá have one of the world's richest populations of breeding aquatic birds. Mývatn and its wetlands are protected as a nature reserve (The Mývatn-Laxá Nature Conservation Area). It is registered as one of the internationally important wetlands, along with the Laxá river which flows out of the lake.