Rescuers waded into London's River Thames Saturday to assess the health of a whale that has been stranded in the river for over a day, as a rescue operation got under way. Earlier on Saturday port authority officials and marine life experts discovered the whale in west London after it disappeared from view in fading light at around 5:30 p.m. Friday. The Port of London Authority's Martin Garside, on a craft alongside the whale, said a rescue operation might be needed to get the animal back to the sea after it appeared to make no attempts to do so on its own. "In the 24 hours since we've seen it, it has gone the wrong way. It's even further from the sea than it was yesterday," he said.