Complex sentence: Brendan's first voyage took him to the Arran Islands, where he founded a monastery, and to many other islands which he only visited, including Hinba (Argyll), an island off Scotland where he is said to have met Columcille (Columba).
Split into simpler sentences: Brendan's first voyage took him to the Arran Islands, where he founded a monastery. He also visited Hinba (Argyll), an island off Scotland where he is said to have met Columcille (Columba).