Ãâskjuvatn Lake is a large lake that fills much of the smaller caldera resulting from the 1875 eruption in Askja. Its surface lies about 50 m below the level of the main crater floor and covers about 12 kmò. When the lake originally formed it was warm, but today it is frozen over for most of the year. Ãâskjuvatn is the second deepest lake in Iceland at 220 m deep