The Bass Rock, or simply The Bass, is an island in the outer part of the Firth of Forth in the east of Scotland. It is approximately 2 kilometres (1.2 mi) offshore, and 5 kilometres (3.1 mi) north-west of North Berwick. It is a steep-sided volcanic rock, 107 metres (351 ft) at its highest point, and is home to a large colony of gannets. The rock is currently uninhabited, but historically has been settled by early Christian hermits, and later was the site of an important royal castle, which was often used as a prison. The island was in the ownership of the Lauder family for many years, and now belongs to the Hamilton-Dalrymple family. A lighthouse was constructed on the rock in 1902, and the remains of a chapel are located there. The Bass Rock features in numerous works of fiction, including Robert Stevenson's Catriona.