Complex sentence: Because of the barren nature of the island, there is no cemetery on the church grounds, and bodies had to be buried elsewhere, typically in the cemetery of Bremsnes church, over ten kilometres away over open sea.
Split into simpler sentences: Because of the barren nature of the island, there is no cemetery on the church ground. The deceased had to be buried elsewhere, typically at the cemetery of Bremsnes church, over 10 km away over open sea.