The Grabensee is an interesting bog lake. It is the smallest of the three Trumer Lakes. There are only a gentle tourist use here. Therefore, the lake is perfect for a quiet and relaxing holiday. The Grabensee characterized - as well as its larger neighbor - a very good water quality. At the south-western shore there is a mud spa. Also, a Kneipp facility is available. A beautifully-idyllic campsite is situated on the northwest shore.

The Grabensee situated within the conservation area and is put under protection.
The Grabensee is a heath and a very warm lake. The average water temperature in summer 20-22 ° C. Water temperatures up to 28 ° C are possible in hot periods.