Listing: New homes for fish. Available immediately. Spacious, great floor plan, located in an excellent neighborhood. Open habitats include airplanes, shipwrecks, concrete pyramids and contemporary fiberglass structures. All dwellings have a spectacular ocean view.

For the last 50 years, some of Hawaii’s most beautiful natural reefs have been disappearing — reefs that are home to more than 7,000 known species of marine plants and animals, one-quarter of which are found nowhere else in the world. These coral reefs have been threatened by alien invasive species, overfishing, land-based pollution, ocean debris and detrimental climate changes.

This year is the International Year of the Reef (IYOR), a global campaign to raise awareness about the conservation and restoration of coral reefs. Locally, the state of Hawaii is partnering with public, private and nonprofit groups to hold a series of events in 2008 that focus on bringing attention to the ecological, social and cultural value of this “rainforest of the sea.”

According to the IYOR website, coral reefs cover less than one percent of the ocean floor but support an estimated 25 percent of marine life. They provide spawning grounds, refuges and feeding areas for all sorts of organisms.

Several attempts have been made to estimate the value of the world’s coral reefs in terms of dollars, according to the website, which lists the total economic assessment between $100,000 to $600,000 per square kilometer per year.

One local company that has invested substantially in helping to rebuild the ocean ecosystem in Hawaii is Atlantis Adventures, operator of submarine undersea explorations for millions of guests who frequent Maui, Oahu and the Big Island.

Atlantis has spent more than one million dollars since 1989 to sink artificial reefs in the submarines’ dive areas to help nurture coral and develop marine life.

The results have been nothing short of phenomenal. A vibrant ecosystem supporting all sorts of indigenous fish, coral, turtles and other marine life has emerged in Waikiki and Kona, and will soon be established in Lahaina as well.

"What I’ve seen of the life that’s been brought back in the 12 years I’ve been with the company is literally huge," says Ronald Williams, president and CEO of Atlantis Adventures. "If the artificial reefs weren’t there, you wouldn’t see any of this life."

The Oahu Atlantis dive site in Waikiki is approximately 5.8 acres and in 1989 consisted of low-growing coral formations spouting up on a volcanic base. "This base provided a solid substrate for the corals to adhere to, but there was also a sparse area of sand flats," explains Mark Almaraz, general manager of Atlantis’ Oahu operations. "Sand flats do not make a hospitable environment for corals due to the shifting substrate and the smothering effects of sand on corals. The artificial reefs deployed in this area provide a habitat consisting of a solid substrate that is above the shifting sand. These developments of coral and algae are the primary stage in the development of a living reef."

Off of Waikiki, Atlantis has sunk concrete pyramid structures, Japanese-designed artificial reefs, two airplanes and the remains of two shipwrecks.