A beluga whale (search) that apparently took a wrong turn made quite a splash in the Delaware River on Tuesday, sending people flocking to the shoreline and out on boats to catch a glimpse.

The 10- to 12-foot oceangoing whale was spotted shortly after noon swimming downstream just south of the city's famed "Trenton Makes The World Takes" bridge, which spans the river at the uppermost reach of its tidal waters.

But the lone whale wasn't alone for long.

By late afternoon, about 100 people were gathered along the banks of the river on the New Jersey side to get a look, images of the whale surfacing and diving were broadcast on the television news and police were fielding calls from passers-by who spotted it.

"I have a perfect view of the Delaware from my office, and this whale is going back and forth from the marina to the bridge," said Paul Loriquet, a spokesman for the state Attorney General's Office, watching the scene unfold from his eighth-floor office.

"Four news helicopters are hovering overhead. The train is stopping on the train trestle, people are lining up along the river. It's like the city has gone mad. They might rename the bridge 'The Beluga Whale Bridge,"' Loriquet said.

At sunset, as the whale continued to swim back and forth between the bridge and a nearby marina, several dozen gawkers stood along the riverbank shouting, "There he is!" and laughing each time the whale surfaced.

Lorenzo Ricks brought his wife and two sons from their home in Bordentown.

"You'll never see anything like this," said Ricks. "This is something else."

But all the excitement was doing more harm than good, according to a marine mammal expert.

"Right now, our major problem is harassment by boaters," said Bob Schoelkopf, director of the Marine Mammal Stranding Center (search) in Brigantine. "People are hearing about it through the press. As a result, it's changing the course of the animal. If it's heading south and people get in front of it, it turns around. It'll never get out of there if they harass it with boats," said Schoelkopf.

He said the whale may be a juvenile that wasn't seaworthy or an adult that chased a school of herring up the river. Typically, beluga whales travel in large groups but spread out when feeding.

"We're working with the National Marine Fisheries Service to determine the health of the animal, assess the area, look for possible areas to capture and remove it to a friendlier area," he said.

State police Capt. Al Della Fave said marine officers were patrolling the river in boats and hoped to herd the whale back south.

The whale had to swim directly past the city of Philadelphia to make it so far north, some 80 miles from the Atlantic Ocean to Trenton, where the river turns too shallow for a creature of its size to continue swimming upstream.

Environmental Department spokeswoman Karen Hershey said she was not sure whether a whale had ever been in the vicinity before.

A right whale — named Waldo the Wrong-Way Right Whale by Philadelphians — straggled into the Delaware River (search) in 1995. The whale beached itself at an oil terminal in Pennsauken, N.J., but disappeared after about 10 days. It was found two years later swimming near Canada.