Modern glass outdoor swimming poolsI found this high class glass residential swimming pool picture while surfing the net, view this image on the on the XenGlass website:
This glass bottom pool can be found at the 1000 Beach estate. A cool design but unfortunately it is built overlooking what seems to be a car park. 
The
Z Oceans Hotel in South Beach, Miami features a pool with triangular glass bottoms. Pretty cool!
Modern indoor swimming poolsThe Casa Rota home, designed by Manuel Ocana, has an awesome indoor swimming pool. There is a painting on the pool's floor and when you look down from the second story, you can see the painting in its totality. 
The world's largest indoor swimming pool
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The 'Ocean Dome' (pictured above) located in Miyazaki, Japan, is the biggest indoor swimming pool in the world. It’s 300 meters long and 100 meters wide. The temperature inside the pavilion is always 30 degrees and the roof is painted to resemble the skye. It also has an artificial volcano and an artificial waves generation system.
Underground pools, thermal baths & spasThis beautiful underground pool is in the
homestead resort in Utah. Sun shine through a central hole in the dome shaped roof, like the Pantheon in Rome.
The Gellért Thermal Baths and Swimming Pool, are a bath complex in Budapest, Hungary, built between 1912 and 1918 in the Art Nouveau style. They were damaged during World War II, but then rebuilt. The Gellért Baths complex includes thermal baths, which are small pools containing water from Gellért hill's mineral hot springs. The water contains calcium, magnesium, hydrocarbonate, alkalis, chloride, sulfate, and fluoride. The complex also includes saunas, plunge pools, children's pool, an effervescent swimming pool and an open-air swimming pool which can create artificial waves every ten minutes.
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wikipedia.org
Hungary is also the home of the famous spa of Miskolctapolca. The unusual thermal cave bath is unique all around Europe. Besides the natural cave bath there are indoor and outdoor pools, an aqua park, thermal pools and a small pool for children. 
Below is an example of a modern take on thermal baths. The architects at the Zurich based
Smolenicky & Partners, designed the Tamina Thermal Baths for the
Grand Resort in Bad Ragaz, Switzerland.
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Image sourceAnother modern design is The Gleichenberg Thermal Bath in Austria
Awesome rooftop swimming poolsBodrum, Turkey boasts this ultra modern 'Exploded House' designed by GAD architects. GAD created a house made from three separate buildings – a metaphor for a single building that has been 'exploded' into many parts. The roof of the building is covered with what looks like swimming pools but are in fact pools that collect rainwater. The water cascades from the roof of one of the buildings to the other and is then circulated back round, creating a natural cooling system for a hot climate. However the house also has a continious swimming pool set at a slightly lower grade from the house.
This roof top pool in Paris, by Rem Koolhaas
OMA is super cool.
The Bali
Four Seasons rooftop pool is exceptional. A wooden bridge takes you over a chasm to an infinity pool with the jungle wrapping around the background. The pool floats 50 feet above the ground. The entrance to the hotel is through a slit in the pool to the lobby underneath.
The
Joule Hotel is a five-star hotel in Dallas famous for it’s swimming pool that partially hangs off the side of the building – eight stories up.
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Image sourceA simular roof top swimming pool can be found at the
Auckland Hilton Hotel in New Zealand.
Strange shaped pools
This is a unique guitar shaped pool.
Pools with a message
In the
photo below of what appears to be a family underwater in a swimming pool is in fact an artistic illusion. The water is not in the pool, it is on top on a glass lid.
A clever ad for HSBC – the bank wanted to raise awareness of the dangers of global warming, so the clever ad agency, Ogilvy & Mather glued an aerial photo of a city’s skyscrapers to the base of a swimming pool creating a view of a submerged cityscape.
The world's deepest pool
At a depth of over 100 ft deep, the pool at the Nemo 33 recreational diving center in Belgium is the worlds deepest recreational pool.
The world's biggest outdoor swimming pool
The San Alfonso del Mar Swimming Pool in Algarrobo, Chile, is the biggest swimming pool in the world.
The enormous crystalline water pool of San Alfonso del Mar measures over one kilometer in length. It covers eight hectares and holds 250 million liters of water. That's the same size as six thousand 8-meter long swimming pools.
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via worldgreatestsites.com
Cool pre-fab swimming poolsThese
pools in Brooklyn are made out of old dumpsters.
This public swimming pool in Berlin called
The Badeschiff floats on the river Spree and is created from a recycled river cargo container. Since its opening in 2004, it has become a true hot spot in town: deep blue swimming pool, wooden boardwalks, an open-air bar, stunning view and a hell of a lot of trendy people. The small 32m by 8m pool is kept to a comfortable 24 degrees Celsius.
© Kendall Waldman
© Kendall WaldmanA
curving translucent shelter and saunas were added recently, making the Badeschiff suitable for winter use.
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Floating swimming pools
The
Barge Beach Budapest in Hungary is a sailing island with an open air pool that is situated in the waterways between the Barge river’s edges. The island beach is constructed from three recycled barges and provides residents with a space to bask in the sun.
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These remarkable floating pools by Mobideep is awesome! They are easily installed, is very low maintenance and extremely enjoyable. Definitely a great way to occupy space such as rivers, lagoons and lakes.
Natural Swimming PoolsClear Water Revival creates some of the best natural pools in the world. A natural swimming pool offers a natural alternative to chemical pools. They are chlorine-free, and harness nature's processes, with microorganisms and plants balancing the water chemistry and maintaining clean, clear and hygienic conditions for natural swimming.
