Naust

In Scandinavia, the boathouse is known as a naust, a word deriving from Old Norse naverstað. These were typically built with stone walls and timber roofs and would be either open to the sea or provided with sturdy doors. The floors would be a simple continuation of the beach sand or rock, or they might be dug down to permit a boat to sail into the boathouse.

https://en.wikipedia.org/wiki/Boathouse
https://no.wikipedia.org/wiki/Naust