Architecture firm Snøhetta has revealed plans to build a restaurant in southern Norway that will be partly submerged in the sea to give diners a glimpse below the waves, reported The Dezeen. Described by the Oslo- and New York-based firm as "Europe's first underwater restaurant", the building will comprise a rugged concrete box with half of its body on the coastline, and the other half sunken underwater. Its primary use will be as a restaurant for up to 100 people, but it will also function as a marine research center and as an artificial mussel reef. Once inside, visitors will be able to look through a huge panoramic window to observe sea life at first hand. The building will be called Under – a word that the architects say is very similar to "wonder", when translated into Norwegian. It will be built near the village of Båly in Norway's Lindesnes region, on the country's southernmost tip. The building's concrete walls will be a meter thick, helping to withstand its inhospitable environment. Externally, this concrete will have a coarse texture, to encourage mussels to attach themselves to the structure. Meanwhile, the marine research center inside will facilitate studies into fish behavior – specifically whether it is possible to train wild fish with sound signals, and also whether fish act differently in different seasons. A huge frame-like oak wall will provide the building's entrance, which will lead through to a wood-lined restaurant space. The dining room will be painted in deep blue and green hues "inspired by the seabed, seaweed and rough sea". There will also be a champagne bar, featuring more subdued tones, intended to evoke shells, rocks and sand. The large panoramic window, measuring 11 meters wide, spans the entire end wall of the space.

It's traditionally played on grass and clay, but could tennis matches one day take place in a waterproof bubble in an "underwater Wimbledon"? An architect Krysztof Kotala from Polish firm 8+8 Concept Studios has released designs for an ambitious project to build an underwater tennis court off the coast of Dubai. He showcased some computer-generated images of the proposed tennis court. An underwater tennis complex could be built just offshore in the Persian Gulf, between the Burj al Arab and the Palm Jumeirah islands. Part sports arena and part aquarium, the eccentric concept for the seven-court complex calls for a rooftop coral reef, which would bring an abundance of sea life to the area for spectators (and players) to view. During his interview to Arabian Business Kotala told that the idea had strong commercial potential and would combine the best of "technology, ecology and sport." An architect is currently seeking investment from local backers to make the concept a reality. "There is not an investor but I would like to get interest as I think it is a good idea," he told Arabian Business. However, although the underwater sports concept looks stunning, engineers have poured water (excuse the pun) on the idea that such a tennis court could be built with current technology. Sarah Fray, director of engineering and technical services at the Institution of Structural Engineers in London, explained that one of the biggest challenges would be to create the large span of glass to cover the court. This would have to be at least 33 meters wide to accommodate the court and spectators. Currently, flat panels of glass can be manufactured in single pieces around 10 meters long - such as panels used in Apple's store in Turkey - but new machinery would have to be invented to make larger panes of curved glass, the type of which would be needed for the design. Another challenge is how to get to the tennis court. She explains that there would have to be a way for the structure to be connected to the surface. However, she conceded that the arched shape of the underwater court is a good idea because it's the best way of resisting pressure, the likes of which would be vast, particularly if the court was submerged at a decent depth beneath the waves. Will Stewart, a Fellow of the Institution of Engineering and Technology (IET) added that the design may not appear as bright inside as the concept images suggest. He explained the glass would have to be many meters thicker at the edges than at the center of the arch, so views of the ocean would not be as bright as they are in the concept pictures. Dubai is no stranger to unusual tennis courts. In 2005, a court was built atop the 305 meters tall Burj al Arab hotel to promote the Dubai Tennis Championships. Besides this Dubai is known for outlandish construction projects including man-made islands and the world's tallest building. It also already has a restaurant - Al Mahara - that's underwater. However the technological challenges are big, but the human challenges are bigger. And in future everything is possible.

If you want to wake up surrounded by water world and fishes, an ongoing project on Dubai's The World Island may just be the perfect choice for you. The Dubai based developer Kleindienst Group, which at first announced about unbelievable artificial islands in the shape of the world 4 kilometers off the coast of Dubai, on February 5 private launch offered potential buyers partially submerged villas on these islands. After official launch 5 underwater villas found its owners. Two of investors are from Europe, while the remaining three are from Gulf Corporation Council (GCC) states and an Indian, with a UAE residency permit. The unusual villas are being built on Monaco Island, part of The Heart of Europe (THOE) project. Each underwater villa initially cost a whopping US$ 1,36 million. The three level villas, with a roof top at the third level and a suite at the bottom floor, submerged nearly 4 meters underwater. The 156 square meters villas are expected to be completed by 2017. THOE will have 42 underwater villas. 20 have been presented, while the developer holds the remaining 22 villas, which it plans to launch at a later stage. The World project is 9 kilometers wide and 7 kilometers long. It covers an area of 931 hectares. The islands range from 14 000 to 42 000 square meters in size. The Heart of Europe comprises six islands: Germany, Austria, Switzerland, Monaco, Sweden and St. Petersburg.

Recently visitors of luxury hotels aren't interested in 5-star hotels, which have spa-centers, fitness-centers and other luxury services. They want to live in original rooms, for example in icy-rooms, or in rooms which are situated on the trees or under the water. The first underwater hotel in Africa has opened off the remote island of Pemba, part of the archipelago of Zanzibar, in Tanzania last week. The hotel is 250 meters out to sea and consists of three floors, including a dining room and an upper deck for star-gazing. The bedroom is below deck completely submerged by water and provides a 360-degree view of sea life. But this isn't new for thus, who likes to relax originally. World's first underwater hotel is situated in Florida, USA. Hotel originally built in the early 1970s as a groundbreaking research lab, and opened for public as hotel only in 1986. The Jules Undersea Lodge. is consists of 2 bedrooms and a dining room. The "cottage-sized" hotel has the comforts of home like hot showers, a kitchen with a refrigerator, air conditioner and so on. Europe's only undersea hotel "Utter Inn" is situated in Sweden. The hotel is consists of a little room, kitchen and toilet. Underwater hotels are still largely a product of a vivid imagination. Several are in the planning stage or are currently under construction. In 2011 was announced that construction work was set to begin on a US$ 500 million semi-submerged resort named Amphibious 1000 on the Qatar coast. Two underwater projects "Water Discus Hotel" and "Hydropolis" were announced in Dubai, but the construction was delayed. Turkey, South Korea, Fiji, China also planning underwater projects. Besides these failures recently Tokyo-based Shimizu Corporation just unveiled blueprints for the world's first underwater city. The Shimizu construction company estimates that the technology to implement the "Ocean Spiral" could be in place by 2030.

After two years of design development, Tokyo-based Shimizu Corporation just unveiled blueprints for the world's first underwater city that, by the construction company's estimates, could be completed in just a few decades at a cost of US$ 26 billion. Dubbed the "Ocean Spiral" the sustainably powered, Atlantis-like metropolis is the latest futuristic scheme proposed by Shimizu. Shimizu Corp.'s vision of the modern-day Atlantis is divided into three parts, with the underwater city contained in a 500 meters wide sphere that could house up to 5,000 residents and comprise mixed-use developments where people can live, work, and play. The spherical city floats at the surface of the sea, but can descend down a 15 kilometers long spiral pathway into the deeper depths during times of bad weather. The spiral pathway is connected to a research facility, which would excavate the seabed for precious metals and create energy for the city above using temperature differences in ocean water. "This is just a blueprint by our company, but we are aiming to develop the technology that would enable us to build an underwater living space," Shimizu spokesman Masataka Noguchi told the Wall Street Journal. Desalinated water would be created using hydraulic pressure and fish farms would be built around the structure. The proposal also mentions harnessing the power of microorganisms to convert carbon dioxide to methane energy. Although seemingly farfetched, Shimizu's proposal underscores fears of sea level rise and loss of habitable environments. The design was realized with help from University of Tokyo researchers, the Japan Agency for Marine-Earth Science and Technology and the government's Fisheries Research Agency. The Shimizu construction company estimates that the technology to implement the "Ocean Spiral" could be in place by 2030.