In the backcountry of Everglades National Park, scientists and park officials are tending to a pod of pilot whales trapped and dehydrated in shallow water. NBC's Mark Potter reports.

With 10 of their podmates already dead, time is running out for more than 40 pilot whales that remain beached off Florida's Gulf Coast, marine biologists said Wednesday.

Staff at Everglades National Park and marine mammal specialists with the National Oceanic and Atmospheric Administration, or NOAA, are desperately working to move the whales into deeper water before low tide returns and strands them again.

About 50 whales were stranded in shallow waters in a remote area of Everglades National Park. Several of the whales have died. Watch aerials.

"They're in really shallow water, kicking up sand, so there's just not enough water for them to get back to sea," Linda Friar, a spokeswoman for the park, told NBC News.

A fishing guide discovered the pod of 51 whales Tuesday afternoon in an area known as Highland Beach. Six of them were found dead Wednesday morning, and four others had to be euthanized.

Many of the survivors may be suffering from dehydration and malnutrition, and they need to make it at least 20 miles to reach waters deep enough to support them, said Blair Mase, Southeast regional director for NOAA's Marine Mammal Stranding Network.

"They're not moving, though. They're staying. They're freely swimming about," Friar said. "They're a species that like to stay together, and we're just not able to get them to move away."

It's unknown why the whales ended up in such shallow waters, said said Liz Stratton, a marine biodiversity specialist and assistant coordinator of the Marine Mammal Stranding Network.

"Sometimes, whales strand because they are sick. Sometimes they strand because they run out of water [or because of] parasites or other problems," Stratton said.

Because pilot whales are highly social creatures it's possible "that some of those animals might stay with their ill podmates rather than swim out to deeper waters," she said

Another big problem is the obstacle course of sandbars between the gulf and the whales, which need to make it at least 20 miles to reach waters deep enough to support them.

Rescuers said it would take at least through Thursday and possibly Friday to complete the mammoth operation. Optimism is low, however, because most mass strandings don't have a successful outcomes.

"It's not a good sign that they're staying so close," Friar said. "They have plenty of water to swim in. They really should've gone ahead and moved out, so that's not a good sign."

Erika Angulo of NBC News contributed to this report.