Iseltwald is a village and municipality on the southern shore of Lake Brienz in the Bernese Oberland region of Switzerland . Politically, the municipality is located in the Interlaken-Oberhasli administrative district of the Canton of Bern .

Iseltwald is first mentioned in 1146 as Iseltwalt.

During the Middle Ages, a castle was built on the peninsula near the village for the Lords of Matten. In 1146, King Conrad III gave Interlaken Monastery one quarter of the village. Over the following years, the monastery attempted to expand their power in the village.