Utter Inn (in English, Otter Inn) is an art project by Mikael Genberg which offers an underwater accommodation for the public. The facility is entered through a typical Swedish red house located on the surface of the water.

The guests of Utter Inn arrive at the port of Vasteras and are taken out one kilometre on Lake Malaren with an inflatable boat. After receiving all the instructions guests need, they are then left alone.

If guests prefer deluxe accommodation, someone can deliver dinner by boat in the evening. Guests can use an inflateable canoe to visit the closest uninhabited island. Guests can also swim, sunbathe or watch the fish (from both upstairs and downstairs) at the hotel. It's a remarkable feeling to go to bed while the fish surround and watch you carefully.