Breiðafjörður is a large shallow bay, about 50 km (31 mi) wide and 125 km (78 mi) long, to the west of Iceland. It separates the region of the Westfjords (Vestfirðir) from the Snæfellsnes peninsula to the south. Breiðafjörður is encircled by mountains, including Kirkjufell and the glacier Snæfellsjökull on the Snæfellsnes peninsula, and the Látrabjarg bird cliffs at the tip of the Westfjords. Numerous smaller fjords extend inland from Breiðafjörður, the largest being Hvammsfjörður at its southeastern corner. An interesting feature of the bay is that the land to the north was formed about 15 million years ago, whereas the land to the south was formed less than half that time ago.. Breiðafjörður therefore was formed by tectonic movements and all the islands and skerries were made by volcanic eruptions to form ridges and craters that mostly line up in a east-west position.