At first glance, this house appears to have simply detached from the mainland and floated away.

However, the Utter Inn ('Otter' in English) is a floating, underwater hotel, where you sleep in an aquarium three metres beneath the surface of Lake Mälaren in Västerås, Sweden.

Local artist Mikael Genberg built the house 12 years ago and the single bedroom contains just two twin beds and a table.

utter inn

According to Unusualhotelsoftheworld.com, the room has panoramic views of the lake's depths and is intended to challenges visitors' perception of fear.

"You don't want to feel afraid so the brain changes the emotion to something far more pleasant. You feel more alive. In this sense arranged, controlled fear can be very important."

Here are some more of the world's best bobbing holiday homes...

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  • Nantucket Lightship

    <a href="http://www.nantucketlightship.com/">Nantucket Lightship</a> A decommissioned lightship -- a craft designed to act as a floating lighthouse -- the Nantucket has been refurbished with mahogany- and cherry-paneled interiors and can now be chartered as a vacation rental in the Northeast, operating out of Martha's Vineyard, Nantucket, Newport and New York City.

  • Nantucket Lightship

    <a href="http://www.nantucketlightship.com/">Nantucket Lightship</a> A decommissioned lightship -- a craft designed to act as a floating lighthouse -- the Nantucket has been refurbished with mahogany- and cherry-paneled interiors and can now be chartered as a vacation rental in the Northeast, operating out of Martha's Vineyard, Nantucket, Newport and New York City.

  • Nantucket Lightship

    <a href="http://www.nantucketlightship.com/">Nantucket Lightship</a> A decommissioned lightship -- a craft designed to act as a floating lighthouse -- the Nantucket has been refurbished with mahogany- and cherry-paneled interiors and can now be chartered as a vacation rental in the Northeast, operating out of Martha's Vineyard, Nantucket, Newport and New York City.

  • Nantucket Lightship

    <a href="http://www.nantucketlightship.com/">Nantucket Lightship</a> A decommissioned lightship -- a craft designed to act as a floating lighthouse -- the Nantucket has been refurbished with mahogany- and cherry-paneled interiors and can now be chartered as a vacation rental in the Northeast, operating out of Martha's Vineyard, Nantucket, Newport and New York City.

  • Soneva Gili

    <a href="http://www.sixsenses.com/soneva-gili/">Soneva Gili</a> From luxury hotel company Six Senses, the Soneva Gili is off the shore of Lankanfushi Island in the Maldives, the low-lying archepelago nation in the Indian Ocean. With 45 over-water villas, its small wonder that some are called "Crusoe Residences," after literature's most famous castaway.

  • Soneva Gili

    <a href="http://www.sixsenses.com/soneva-gili/">Soneva Gili</a> From luxury hotel company Six Senses, the Soneva Gili is off the shore of Lankanfushi Island in the Maldives, the low-lying archepelago nation in the Indian Ocean. With 45 over-water villas, its small wonder that some are called "Crusoe Residences," after literature's most famous castaway.

  • Soneva Gili

    <a href="http://www.sixsenses.com/soneva-gili/">Soneva Gili</a> From luxury hotel company Six Senses, the Soneva Gili is off the shore of Lankanfushi Island in the Maldives, the low-lying archepelago nation in the Indian Ocean. With 45 over-water villas, its small wonder that some are called "Crusoe Residences," after literature's most famous castaway.

  • Soneva Gili

    <a href="http://www.sixsenses.com/soneva-gili/">Soneva Gili</a> From luxury hotel company Six Senses, the Soneva Gili is off the shore of Lankanfushi Island in the Maldives, the low-lying archepelago nation in the Indian Ocean. With 45 over-water villas, its small wonder that some are called "Crusoe Residences," after literature's most famous castaway.

  • River Kwai Jungle Raft

    <a href="http://www.riverkwaijunglerafts.com">River Kwai Jungle Raft</a> Floating since 1976, this raft of rooms snakes its way down the River Kwai, less than three hours from Bangkok. Individual rafts support each room, each of which has an outdoor deck complete with hammock. In a nod to the area's ethnic culture, the hotel makes an effort to employ local Mon people.

  • River Kwai Jungle Raft

    <a href="http://www.riverkwaijunglerafts.com">River Kwai Jungle Raft</a> Floating since 1976, this raft of rooms snakes its way down the River Kwai, less than three hours from Bangkok. Individual rafts support each room, each of which has an outdoor deck complete with hammock. In a nod to the area's ethnic culture, the hotel makes an effort to employ local Mon people.

  • River Kwai Jungle Raft

    <a href="http://www.riverkwaijunglerafts.com">River Kwai Jungle Raft</a> Floating since 1976, this raft of rooms snakes its way down the River Kwai, less than three hours from Bangkok. Individual rafts support each room, each of which has an outdoor deck complete with hammock. In a nod to the area's ethnic culture, the hotel makes an effort to employ local Mon people.

  • River Kwai Jungle Raft

    <a href="http://www.riverkwaijunglerafts.com">River Kwai Jungle Raft</a> Floating since 1976, this raft of rooms snakes its way down the River Kwai, less than three hours from Bangkok. Individual rafts support each room, each of which has an outdoor deck complete with hammock. In a nod to the area's ethnic culture, the hotel makes an effort to employ local Mon people.

  • Amstel Botel

    <a href="http://www.amstelbotel.nl/en/">Amstel Botel</a> A natural fit for canal-filled Amsterdam, the massive Botel has 175 cabins with rooms for less than €100 per night, not a bad rate for the European capital. An on-board bar stays open late, offering ample opportunity to lift glasses with your fellow passengers.

  • Amstel Botel

    <a href="http://www.amstelbotel.nl/en/">Amstel Botel</a> A natural fit for canal-filled Amsterdam, the massive Botel has 175 cabins with rooms for less than €100 per night, not a bad rate for the European capital. An on-board bar stays open late, offering ample opportunity to lift glasses with your fellow passengers.

  • Amstel Botel

    <a href="http://www.amstelbotel.nl/en/">Amstel Botel</a> A natural fit for canal-filled Amsterdam, the massive Botel has 175 cabins with rooms for less than €100 per night, not a bad rate for the European capital. An on-board bar stays open late, offering ample opportunity to lift glasses with your fellow passengers.

  • Amstel Botel

    <a href="http://www.amstelbotel.nl/en/">Amstel Botel</a> A natural fit for canal-filled Amsterdam, the massive Botel has 175 cabins with rooms for less than €100 per night, not a bad rate for the European capital. An on-board bar stays open late, offering ample opportunity to lift glasses with your fellow passengers.

  • Boat Hotel Fortuna

    <a href="http://www.ohb.hu/fortuna/index.en.html">Boat Hotel Fortuna</a> A river city like Budapest is well suited to a floating hotel like this, a 84-room boat, docked on the Pest side of the Danube. Rooms may tend to the small side -- and hostel-like accommodations on one deck are thin on comforts -- but the location near the park on Margit Island is a big plus.

  • Boat Hotel Fortuna

    <a href="http://www.ohb.hu/fortuna/index.en.html">Boat Hotel Fortuna</a> A river city like Budapest is well suited to a floating hotel like this, a 84-room boat, docked on the Pest side of the Danube. Rooms may tend to the small side -- and hostel-like accommodations on one deck are thin on comforts -- but the location near the park on Margit Island is a big plus.

  • Punta Caracol

    <a href="http://www.puntacaracol.com/">Punta Caracol</a> This series of over-water villas look more Polynesian than Central American but visitors nevertheless find them floating among the sparsely populated islands of Panama's Bocas del Toro. Built from native materials, the nine cabins have solar panels and sensitive water treatment systems with an eye toward protecting the surrounding Caribbean Sea.

  • Punta Caracol

    <a href="http://www.puntacaracol.com/">Punta Caracol</a> This series of over-water villas look more Polynesian than Central American but visitors nevertheless find them floating among the sparsely populated islands of Panama's Bocas del Toro. Built from native materials, the nine cabins have solar panels and sensitive water treatment systems with an eye toward protecting the surrounding Caribbean Sea.

  • Punta Caracol

    <a href="http://www.puntacaracol.com/">Punta Caracol</a> This series of over-water villas look more Polynesian than Central American but visitors nevertheless find them floating among the sparsely populated islands of Panama's Bocas del Toro. Built from native materials, the nine cabins have solar panels and sensitive water treatment systems with an eye toward protecting the surrounding Caribbean Sea.

  • CPH Living

    <a href="http://www.cphliving.com/pagei.html">CPH Living</a> Docked canal-side in Copenhagen's eclectic Christianshavn neighborhood, CPH Living is a limited-service hotel that nevertheless exudes boatloads of Scandinavian chic. A small breakfast room offers one place to hang out but the real draw is the rooftop sundeck, complete with lounge chairs and killer views of the city skyline.

  • CPH Living

    <a href="http://www.cphliving.com/pagei.html">CPH Living</a> Docked canal-side in Copenhagen's eclectic Christianshavn neighborhood, CPH Living is a limited-service hotel that nevertheless exudes boatloads of Scandinavian chic. A small breakfast room offers one place to hang out but the real draw is the rooftop sundeck, complete with lounge chairs and killer views of the city skyline.

  • CPH Living

    <a href="http://www.cphliving.com/pagei.html">CPH Living</a> Docked canal-side in Copenhagen's eclectic Christianshavn neighborhood, CPH Living is a limited-service hotel that nevertheless exudes boatloads of Scandinavian chic. A small breakfast room offers one place to hang out but the real draw is the rooftop sundeck, complete with lounge chairs and killer views of the city skyline.

  • De Barge

    <a href="http://www.hoteldebarge.be/index.asp?taal=en">De Barge</a> The canals of Medieval Bruges are a natural fit for this impeccably designed boat hotel and restaurant. Sailboat-inspired rooms have navy-and-white color palattes and beds are stacked with pillows <em>and</em> lifejackets. Mirrors set inside porthole fittings are a particularly whimsical touch.

  • De Barge

    <a href="http://www.hoteldebarge.be/index.asp?taal=en">De Barge</a> The canals of Medieval Bruges are a natural fit for this impeccably designed boat hotel and restaurant. Sailboat-inspired rooms have navy-and-white color palattes and beds are stacked with pillows <em>and</em> lifejackets. Mirrors set inside porthole fittings are a particularly whimsical touch.

  • Boggsville Boatel

    <a href="http://www.fluxfactory.org/events/constance-hockaday%E2%80%99s-boggsville-boatel-and-boat-in-theater/">Boggsville Boatel</a> A seasonal art project in Jamaica Bay, Queens, the boatel is a collection of six vintage pleasure boats assembled by artist Constance Hockaday. With whole boats, many of which can sleep four comfortably, going for $50-$100 a night, this could be one of the cheapest -- and coolest -- hotels in New York City. The not-for-profit art installation plans to return for the summer of 2012.

  • Boggsville Boatel

    <a href="http://www.fluxfactory.org/events/constance-hockaday%E2%80%99s-boggsville-boatel-and-boat-in-theater/">Boggsville Boatel</a> A seasonal art project in Jamaica Bay, Queens, the boatel is a collection of six vintage pleasure boats assembled by artist Constance Hockaday. With whole boats, many of which can sleep four comfortably, going for $50-$100 a night, this could be one of the cheapest -- and coolest -- hotels in New York City. The not-for-profit art installation plans to return for the summer of 2012.

  • Boggsville Boatel

    <a href="http://www.fluxfactory.org/events/constance-hockaday%E2%80%99s-boggsville-boatel-and-boat-in-theater/">Boggsville Boatel</a> A seasonal art project in Jamaica Bay, Queens, the boatel is a collection of six vintage pleasure boats assembled by artist Constance Hockaday. With whole boats, many of which can sleep four comfortably, going for $50-$100 a night, this could be one of the cheapest -- and coolest -- hotels in New York City. The not-for-profit art installation plans to return for the summer of 2012.

  • Boggsville Boatel

    <a href="http://www.fluxfactory.org/events/constance-hockaday%E2%80%99s-boggsville-boatel-and-boat-in-theater/">Boggsville Boatel</a> A seasonal art project in Jamaica Bay, Queens, the boatel is a collection of six vintage pleasure boats assembled by artist Constance Hockaday. With whole boats, many of which can sleep four comfortably, going for $50-$100 a night, this could be one of the cheapest -- and coolest -- hotels in New York City. The not-for-profit art installation plans to return for the summer of 2012.

  • Boggsville Boatel

    <a href="http://www.fluxfactory.org/events/constance-hockaday%E2%80%99s-boggsville-boatel-and-boat-in-theater/">Boggsville Boatel</a> A seasonal art project in Jamaica Bay, Queens, the boatel is a collection of six vintage pleasure boats assembled by artist Constance Hockaday. With whole boats, many of which can sleep four comfortably, going for $50-$100 a night, this could be one of the cheapest -- and coolest -- hotels in New York City. The not-for-profit art installation plans to return for the summer of 2012.

  • Boggsville Boatel

    <a href="http://www.fluxfactory.org/events/constance-hockaday%E2%80%99s-boggsville-boatel-and-boat-in-theater/">Boggsville Boatel</a> A seasonal art project in Jamaica Bay, Queens, the boatel is a collection of six vintage pleasure boats assembled by artist Constance Hockaday. With whole boats, many of which can sleep four comfortably, going for $50-$100 a night, this could be one of the cheapest -- and coolest -- hotels in New York City. The not-for-profit art installation plans to return for the summer of 2012.

  • King Pacific Lodge

    <a href="http://www.kingpacificlodge.com/">King Pacific Lodge</a> Hidden in the wilds of British Columbia, the King Pacific is only accessible by float plane, a resort removed from civilization but still heavy on the luxury. Operated by high-end hoteliers Rosewood, all the standard resort amenities are here, along with above-and-beyond offerings that include deep-sea Chinook salmon fishing and heli-yoga, a chopper flight to a nearby glade surrounded by mountains and glaciers for a private -- and no doubt breathtaking -- stretching session.

  • King Pacific Lodge

    <a href="http://www.kingpacificlodge.com/">King Pacific Lodge</a> Hidden in the wilds of British Columbia, the King Pacific is only accessible by float plane, a resort removed from civilization but still heavy on the luxury. Operated by high-end hoteliers Rosewood, all the standard resort amenities are here, along with above-and-beyond offerings that include deep-sea Chinook salmon fishing and heli-yoga, a chopper flight to a nearby glade surrounded by mountains and glaciers for a private -- and no doubt breathtaking -- stretching session.

  • Floatel

    <a href="http://floatelhotel.com/about_us.htm">Floatel</a> Set in the River Hooghly in Kolkata, this 49-room property claims to be India's only floating hotel -- though there's at least one other, in Kerala, later in this slideshow. Open-air banquet halls and a promenade deck make the Floatel well-suited to parties, but it's downtown riverside location makes it a suitable base for exploring the city, with many attractions just a short walk away.

  • Floatel

    <a href="http://floatelhotel.com/about_us.htm">Floatel</a> Set in the River Hooghly in Kolkata, this 49-room property claims to be India's only floating hotel -- though there's at least one other, in Kerala, later in this slideshow. Open-air banquet halls and a promenade deck make the Floatel well-suited to parties, but it's downtown riverside location makes it a suitable base for exploring the city, with many attractions just a short walk away.

  • Sun Boat IV

    <a href="http://www.abercrombiekent.com/travel-destinations/middle-east-luxury-travel/egypt/luxury-nile-cruise-on-sun-boat-IV-4.cfm">MS Sun Boat IV</a> Admittedly more cruise ship than floating hotel, the Sun Boat IV plies the waters of the Nile for tour operator Abercrombie & Kent. Floor-to-ceiling windows offer great views of the coastline from staterooms, while guests can swim al fresco in a tiled swimming pool on the Sun Deck.

  • Sun Boat IV

    <a href="http://www.abercrombiekent.com/travel-destinations/middle-east-luxury-travel/egypt/luxury-nile-cruise-on-sun-boat-IV-4.cfm">MS Sun Boat IV</a> Admittedly more cruise ship than floating hotel, the Sun Boat IV plies the waters of the Nile for tour operator Abercrombie & Kent. Floor-to-ceiling windows offer great views of the coastline from staterooms, while guests can swim al fresco in a tiled swimming pool on the Sun Deck.

  • Yavari

    <a href="http://www.yavari.org">Yavari</a> On Lake Titicaca, this is likely the highest floating hotel in the world, a fine distinction in its own right. But the Guardian calls it "<a href="http://www.guardian.co.uk/travel/2011/sep/07/yavari-lake-titicaca-peru-hotel-bandb">the best bed and breakfast in South America</a>," a $38-a-night stay in otherwise dreary Puno, the southern city that's the gateway to the Peruvian shores of the lake.

  • Yavari

    <a href="http://www.yavari.org">Yavari</a> On Lake Titicaca, this is likely the highest floating hotel in the world, a fine distinction in its own right. But the Guardian calls it "<a href="http://www.guardian.co.uk/travel/2011/sep/07/yavari-lake-titicaca-peru-hotel-bandb">the best bed and breakfast in South America</a>," a $38-a-night stay in otherwise dreary Puno, the southern city that's the gateway to the Peruvian shores of the lake.

  • Jugendgaesteschiff Rostock

    <a href="http://www.huffingtonpost.com/social/buts_parisi"><img style="float:left;padding-right:6px !important;" src="http://s.huffpost.com/images/profile/user_placeholder.gif" /></a><a href="http://www.huffingtonpost.com/social/buts_parisi">buts parisi</a>:<br />Floating and eating full board for a fraction of the money you pay in the other maritime hotels. The youth hostel is in the centre of Rostock/Germany at the Baltic Sea. Nothing fancy, just very authentic and charming.

  • MV Apsara

    <a href="http://www.theparkhotels.com/kerala/the-park-mv-apsara.html">MV Apsara</a> An offshoot of the Park on Vembanad hotel in India's southern tip, the Apsara offers eight contemporary-chic cabins. Docked on Lake Kerala, the hotel offers three-night cruises around the lake's backwaters, for an utterly tranquil tour of this less-traveled part of the country.

  • MV Apsara

    <a href="http://www.theparkhotels.com/kerala/the-park-mv-apsara.html">MV Apsara</a> An offshoot of the Park on Vembanad hotel in India's southern tip, the Apsara offers eight contemporary-chic cabins. Docked on Lake Kerala, the hotel offers three-night cruises around the lake's backwaters, for an utterly tranquil tour of this less-traveled part of the country.

  • Malardrottningen

    <a href="http://malardrottningen.se/home.aspx">Malardrottningen Hotel</a> First built in 1924, this yacht was at one time owned by Woolworth heiress Barbara Hutton and then the British Royal Navy, before being docked quay-side in Stockholm, a stone's throw from Riddarholmen Church. This being Scandinavia, there is --in addition to 61 cabins -- an on-board sauna for guest use.

  • Malardrottningen

    <a href="http://malardrottningen.se/home.aspx">Malardrottningen Hotel</a> First built in 1924, this yacht was at one time owned by Woolworth heiress Barbara Hutton and then the British Royal Navy, before being docked quay-side in Stockholm, a stone's throw from Riddarholmen Church. This being Scandinavia, there is --in addition to 61 cabins -- an on-board sauna for guest use.

  • Utter Inn

    <a href="http://www.vasterasmalarstaden.se/sv/hotell_utter_inn__hotel_otter_inn__a2231_s791.html">Utter Inn</a> This single-room floating cabin near Stockholm in Lake Mälaren is more architectural funhouse than hotel, a concept by artist Mikael Genberg. A small stereotypical Swedish cabin above water gives way to below-the-surface sleeping quarters complete with windows for spying on fish.

  • Reefsleep

    The Great Barrier Reef's <a href="http://www.fantasea.com.au/page/reefsleep/">Reefsleep experience</a> lets snorkelers and scuba divers spend the night out on the water, 40 nautical miles from the mainland. In addition to two air conditioned rooms, the Reefsleep also offers an underwater viewing chamber and an above-water sightseeing platform. Best of all, though, is that all other divers leave by mid-afternoon, leaving guests blissfully alone out at the Hardy Reef.

  • Hôtel Palafitte is on the Neuchâtel Lake in Switzerland, one of the only over-water hotels in Europe. The five-star property offers plenty of quiet, with 24 individual suites floating above the lake -- each tricked out with appropriately bleeding-edge electronics and coffeemakers befitting a luxe Swiss hotel.

  • Hôtel Palafitte is on the Neuchâtel Lake in Switzerland, one of the only over-water hotels in Europe. The five-star property offers plenty of quiet, with 24 individual suites floating above the lake -- each tricked out with appropriately bleeding-edge electronics and coffeemakers befitting a luxe Swiss hotel.

  • Hôtel Palafitte is on the Neuchâtel Lake in Switzerland, one of the only over-water hotels in Europe. The five-star property offers plenty of quiet, with 24 individual suites floating above the lake -- each tricked out with appropriately bleeding-edge electronics and coffeemakers befitting a luxe Swiss hotel.

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