Obertrumersee 503m, has a water area of 4,9 km² and is the largest of the lakes Trummer. The catchment area around the lake is about 58 km². Communities on the lake are Seeham - Obertrum - Mattsee. View from Kaelberpoint in Seeham in direction south of the lake. Info http://www.seeham-info.at.