7 FEATS OF UNDERWATER ENGINEERING

Building in the Deep: 7 Feats of Underwater Engineering
By Laura Kiniry, Popular Mechanics, 4 July 2012.

Giving new meaning to "Under the Sea," these structures are designed to not only survive underwater but to thrive there.

1. Poseidon Resorts, Fiji

While construction has been on hold for years, Poseidon will have no trouble hooking guests if it's ever completed. Plans call for 24 undersea suites with 4-inch-thick transparent plexiglass windows to let guests take in the world under the sea. Although all the suites will be connected to a permanently fixed main corridor, they'll be detachable stand-alone modules that can resurface if necessary.

Visitors would access Poseidon's suites airlocks with carbon fibre doors. This form of entry and exit allows the resort to keep its interior at surface pressure, lessening the possibility of any physiological side effects such as decompression.

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2. Water Discus Hotel, Dubai

Dubai is no stranger to extreme feats of engineering, and its Water Discus Hotel aims to become the first underwater lodging in the emirate. The structure will include both an above-water and below-water section (both are disc-shaped like something out of Star Wars, but their actual sizes aren't yet determined). The above-water disc will be connected to a series of satellite discs housing the hotel's spa, garden, and swimming pool. The below-water disc features 21 two-person rooms, a dive centre, and a bar that will let you drink with the fishes. A vertical shaft containing an elevator and a staircase will offer access between the two.

Design mechanics call for five solid legs to extend down from the lower disc and stabilize the structure on the seabed, while keeping it easily mobile in case the undersea portion needs to resurface for repairs. In the unlikely event of flooding, the hotel's satellite discs are buoyant and can be released and used as flotation devices. Additional high-tech perks include underwater internet and an upper-deck landing pad for helicopters. Oh, and the hotel rotates.

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3. Ithaa Undersea Restaurant, Maldives

Seafood takes on new meaning at Rangali Island's underwater restaurant, a 14-seat eatery located 16 feet below the water's surface. The boat-size structure is encased in a transparent acrylic tunnel offering 270-degree exterior views, so it's almost like dining in a fish tank. Visitors descend into the restaurant via a spiral staircase that's located in a thatched pavilion at the end of a jetty.

Ithaa was built in Singapore and then transported to the Maldives, where workers situated the 175-ton structure on the sea floor by filling it with 85 tons of sand ballast. They then attached the restaurant to four steel piles (each of which had been vibro-hammered approximately 15 feet into the seabed) with concrete.

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4. Aquarius Reef Base, Florida Keys, USA

Underwater research laboratories, more popular in the 1960s and '70s, have gone out of style. Aquarius is the only one still operating. Owned by the National Oceanic and Atmospheric Administration (NOAA) and operated by the University of North Carolina, Wilmington, Aquarius is an 80-ton cylindrical chamber located 63 feet underwater and 3-1/2 miles offshore. It's attached to a 116-ton base-plate for stability.

The laboratory is divided into a live and work area, Main Lock, and an Entry Lock that contains a bathroom, electrical panels, and communications and life support systems. These two parts are then connected by an air lock. Aquarius also has a wet porch that offers entry to the sea through a moon pool, which keeps the chamber at ambient pressure - the same pressure as the water outside. This overall design lets workers return to the surface without having to use a decompression chamber.

5. Jules' Undersea Lodge, Key Largo, Florida, USA

What began in the early '70's as La Chalupa Research Laboratory has been an undersea lodge for the past 30 years. Guests dive down to the submersed hotel and enter via a 5 x 7–foot moon pool at the bottom of the structure, 21 feet below the sea's surface. Compressed air keeps the lodge from flooding.

Despite the lodge's lack of above-water entry you don't have to be a certified diver to stay overnight. While non-certified divers once descended to the lodge by breathing air pumped through a large hose, Jules' now offers a 3-hour course to assure safe entry.

6. BioSUB, Australia

Though built as a temporary structure, BioSUB helped show the world what it's like to live underwater. In 2007, Australian marine biologist Lloyd Godson spent nearly two weeks in the 10-foot-long yellow steel box, 15 feet beneath the surface of a lake. BioSUB's energy came from a mix of onshore solar panels and Godson's pedal power. Oxygen came via an onsite algae garden housed in a biocoil. (It's a coiled plastic tube that acts as a gas-exchange system and runs on carbon dioxide, light, and water - in this case, Godson's own urine.)

7. Cancun Underwater Museum (MUSA), Mexico

Opened to the public in November 2009, the Cancun Underwater Museum features more than 400 life-size sculptures sitting on the sea floor in 28 feet of water. It's a museum without walls, and each work of art is made from pH neutral clay that encourages the growth of corals and attracts sea life so the sculptures will grow and change over time.

Artist Jason de Caires Taylor plans to add 63 new pieces to the museum this July, including a kinetic sculpture boasting wings made of living fan coral and The Listener, which features an underwater device that projects nearby sounds. MUSA is accessible to divers and snorkelers.

Top image: Water Discus Hotel, Dubai (left) and Ithaa Undersea Restaurant, Maldives (right).

[Source: Popular Mechanics. Edited. Top image and some links added.]