(AP) -- Hundreds of people are working around the clock to clean up a lake in the heart of Vietnam's capital in hopes of saving a rare, ailing giant turtle that is considered sacred.
Experts say pollution at Hanoi's Hoan Kiem Lake is killing the giant freshwater turtle, which has a soft shell the size of a desk. It is one of the world's most-endangered species, with only four believed alive worldwide.
Teams of people are cleaning debris, pumping fresh water into the lake and building an artificial island to serve as a "turtle hospital." The rescuers may even try to net the beast for the first time as part of the effort.
The Hoan Kiem turtle is rooted in Vietnamese folklore, and some even believe the creature that lives in the lake today is the same mythical turtle that helped a Vietnamese king fend off the Chinese nearly six centuries ago.
The creature in Hanoi's lake swims alone and in the past has been glimpsed only rarely sticking its wrinkled neck out of the water.
But it has recently surfaced much more frequently, alarming the public with glimpses of raw open wounds on its head and legs.
Meetings were called, a council was established and 10 government agencies were put to work to try to save it.
It's the first time anyone has tried to capture the turtle, and Vietnamese have flocked to the lake in hopes of spotting it - a sign of good luck - as newspapers run daily articles about its plight.
"For the Vietnamese, the Hoan Kiem lake turtle is the most sacred thing," said retired state employee Nguyen Thi Xuan, 63, who traveled from a suburban district to try to get a glimpse of the beast. "He has helped the Vietnamese to defeat foreign invaders and also helped the country to have peace. I hope he will live forever."
The lake, which measures one mile (1.6 kilometers) is a city landmark for its curved red bridge leading to a temple on a tiny island. Weeping willows and other leafy trees shade a sidewalk that rings the water, a popular site for tourists and Hanoians to exercise and relax.
But the lake has been trashed with everything from bricks and concrete to plastic bags and raw sewage. It is not uncommon to see men urinating directly into the murky water.
The pollution is slowly killing the Hoan Kiem turtle, a Vietnamese scientist said.
"I believe the injuries were caused by sharp edges from debris in the lake," said Ha Dinh Duc, who has studied the lone turtle for 20 years and considers himself its caretaker. "The poor quality of water also makes the conditions unbearable for the turtle."
Duc said small red-eared turtles, which are popular pets, also have been released into the lake. They are believed to be feeding on the giant turtle's festering wounds, which may be worsening the infection.
The turtle rescue team hopes to coax the beast onto land so they can treat the wounds.
Sandbags have been built up to create a small island for it to emerge. But if it does not crawl onto the platform by itself, a net will be used to capture it.
Veterinarians will then work at the so-called "turtle hospital" to take skin and shell samples for analysis, and will then determine how to treat it. Photos reveal scars and pink open sores on its head and legs. A white fungus also covers a large section of its shell.
No one knows the turtle's age or gender, but scientists say it is probably the most endangered freshwater turtle species in the world. It weighs about 440 pounds (200 kilograms) and its massive shell stretches 6 feet long (1.8 meters long) and 4 feet wide (1.2 meters wide).
Legend has it that in the mid-15th century, King Le Loi defeated Chinese invaders with a magic sword given to him by the gods. After the victory, the king was said to be boating on the lake when a giant golden turtle rose to the surface and snatched the sword in its mouth before plunging deep into the water to return it to its divine owners.
The lake was later renamed "Ho Hoan Kiem," which means "Lake of the Returned Sword," and the tale became an important part of Vietnamese culture that continues to be taught in school and performed at popular water puppetry shows.
But real or mythical, the turtle that swims in the lake is a legend to the Vietnamese people who call him "cu rua," a word of great respect reserved for great-grandfathers.
"I prayed at a temple this morning hoping to have a glimpse of him," said Vu Thi Dung, a 58-year-old farmer who traveled 60 miles (100 kilometers) for her opportunity to see the turtle. "I had a chance to see him three times already. I'm really glad. It's urgent to treat him and clean up the lake."
Explore further: Thirty new marine protected areas declared in Scotland