Austdalsvatnet is a lake in the northwestern part of Luster Municipality in Vestland county, Norway. It is located in the Breheimen mountain range at the end of the Austdalsbreen glacier, just north of the lake Styggevatnet. It is about 10 km east of Lodalskåpa and Brenibba, in the Jostedalsbreen glacier. The water is regulated by a dam on lake Styggevatnet and it empties into the Jostedøla river which flows south into the Gaupnefjord (part of the Sognefjord).