The Schnittlauchinsel (German, lit.

It is the only island in the lake and among the largest in the canton of St. Gallen.

Its highest point is 420 metres above sea level, only 1 metre above lake level (419 m).

The minimum distance from the shore is about 320 metres.

Politically, the island belongs to the municipality of Quarten in the district of Sarganserland.