Svarthammarhola is a limestone cave in the rugged country outside Bodo, better suited to guided exploration than casual wandering. Its draw is the contrast with the open Nordland coast: one moment you are in wind and wide light, the next you are underground in tight rock passages and cold still air.
Go only with a qualified guide and proper gear. The cave is worthwhile for travelers who want a physical, weatherproof adventure, but it is not a show cave with paved paths and bright lights. Expect mud, helmets, and a trip that depends on local conditions.