Havets hus, Public aquarium in Lysekil, Sweden

Havets Hus is a public aquarium in a coastal town featuring marine species in large tanks filled directly with water from the North Sea and Gullmarsfjorden. The tanks allow visitors to observe hundreds of fish species and other marine organisms in conditions close to their natural habitats.

Havets hus opened in 1993 as a public aquarium in Lysekil, built to show animals from the Gullmarn fjord and the waters off Sweden's west coast. It gained wider attention after appearing in the 1994 TV series Håll huvet kallt, which helped raise tourist numbers from summer 1995. Its salt water is drawn continuously from Gullmarsfjorden at a depth of 32 metres.

The name means "House of the Sea" in Swedish. In 2010 the aquarium ran a themed exhibition called "Sea Monsters", which included the legendary "Gullmarn sea serpent". The facility also offers seal safaris, guided tours and a shop.

The visit runs from the shoreline zone down through the marine environments of the North Sea to the deep seabed, so allow time to follow the route in order. The aquarium is open daily year-round. Besides the tanks, the site has seal safaris, guided tours, mini-golf, a shop and a restaurant.

The tunnel aquarium holds 140,000 litres of salt water, the largest of the roughly 40 tanks, which range down to small aquariums of 70 litres. Water is drawn continuously from Gullmarsfjorden at a depth of 32 metres, with a salinity of 30–33 per mille. In 2010 the temporary exhibition was devoted to "sea monsters", including the legendary Gullmarn sea serpent.