The Großer Eutiner See is a lake in Holstein Switzerland, Schleswig-Holstein, Germany.

It has an area of 230 hectares (570 acres), is up to 17 metres deep and lies at a height of about 26.7 m above sea level (NN).

In the western part of the lake, separated by the Bebensund Bridge, the Fissauer Bucht, its main inflow, the River Schwentine enters, and then leaves again a little further west.

For boating enthusiasts the Schwentine is only navigable upstream as far as the Großer Eutiner See.

Musicals take place during the summer in the castle garden on the shore of the Großer Eutiner See.