Ten short-finned pilot whales are dead after a pod of 51 of the mammals swam into shallow water in a remote region of Everglades National Park in southern Florida, and the outlook is grim for the rest of the pod, as difficult marine terrain may make it impossible for them to get out.

Linda Friar, a spokeswoman for the Everglades National Park, told Nature World News the area where the whales are stranded is "several football fields" long and marked by shallow shoreline. It is unclear exactly how long the wayward pod has been trapped in the shallows around Highland Beach, which is on the Gulf of Mexico side of the park. The landscape of the area is carved by a series of bays and keys, with numerous rivers emptying into the Gulf.

The first report of the stranding came late in the afternoon Tuesday, but because of the beach's extremely remote location - more than an hour away by boat from the nearest boat ramp - a rescue effort could not begin until Wednesday.

A team of 25 rescuers from marine mammal stranding network organizations arrived on the scene Wednesday to find six of the whales dead. Another four showed no signs of reflexes or active responses and were deemed in such poor condition that rescuers had to humanely euthanize them, according to Blair Mase, a marine mammal stranding coordinator with NOAA who spoke to reporters in a telephone news conference.

Mase said that the remaining 41 whales are freely swimming and that they are not stranded or showing any signs of injury or trauma. They seem to be lingering in the shallow water, she said. But short-finned pilot whales are a deep-ocean species, and the 20 miles of marine terrain between deep open water and mere feet of shallow beach water is marked by a series of sand bars, flats and channels that will make the whales' return to deep water challenging, even during high tide.

While the goal of the rescue team is to save the wayward whales, Mase said that outcome is unlikely. The beach's remote location makes it hard for rescuers to bring in the heavy equipment typically used to save stranded whales, and the difficult terrain between the beach and open water makes it less likely that the whales will be able to swim out on their own.

Researchers are currently conducting necropsies on the deceased whales to see if a reason why they came so close to shore can be determined. Short-finned pilot whales are the most common species that strands en mass in Florida, Mase said, adding that the whales are very social creatures and that if a member of the pod is ill and beaches itself, the remaining members of the pod will typically stick by.

But time and geography are working against the whales.

"We don't' know how long they've been out of home range," Mase said, adding that the effects of being out of their habitat are taking a toll on the whales. "The outlook does not ultimately look good for the remaining live whales."

Rescuers plan to return to the scene Thursday and reassess the situation.