The St. Beatus Caves sit above the north shore of Lake Thun, close enough to Interlaken to make an easy half-day trip. About a kilometre of the cave system is open to visitors, with lit paths leading past stalactites, grottoes, underground water, and viewpoints back toward the lake.
The approach is part of the appeal: the path climbs past cascades and into the cliff before the cave tour begins. It is a practical bad-weather option, but the lake setting and the old legend of Saint Beatus give it more character than a generic cave visit.