The main lagoon measures about 20 km2 and until 1932 was covered in thick glacial ice. Then the glacier started to retreat, and nowadays more than 100 m. of ice breaks away each year, to reshape the lagoon and fill it with spectacular icebergs.
The lagoon is open to the sea and so contains a mixture of salt and freshwater, giving it a unique blue-green color. There are hundreds of seals here in the winter and the lagoon supports many species of fish including krill, herring, trout and occasionally salmon.