Captain Adam Murphy, who at the time was operating a commuter boat from Boston to Hingham, first received a report from a second boat on the harbor that the whale was swimming just beyond the Hyatt Regency hotel, near Logan International Airport. Shortly after, Murphy said, he saw the young whale himself.

A whale watch captain said Wednesday that he spotted a juvenile humpback whale swimming a quarter-mile off the tip of Castle Island in Boston Harbor.

It came and went, with a puff of its blowhole.

“I was no more than 70 to 80 feet away from it when it popped up,” Murphy said.


Murphy, who works for Boston Harbor Cruises and has been a whale watch captain for more than a decade, said there was no mistaking the humpback whale.

He said he identified it by its dorsal fin, and the “short, bushy blow” of air it released from its blowhole when it surfaced briefly.

“It might have been in search of food or some warmer water,” he said, adding that the whale was heading “outbound” toward the open sea. “It happened so fast.”

Tony LaCasse, a spokesman for the New England Aquarium, said another captain had also reported the sighting to the Aquarium Wednesday morning. It wasn’t clear if that captain was the one whom Murphy had heard on the radio.

LaCasse said the sighting marked the third time since 2013 that a young humpback had been seen swimming in the harbor area.

Prior to that, in his 12 years as an employee at the Aquarium, only one other juvenile whale ventured close to Boston, LaCasse said. In 2005, he said, “the most famous one” spent three days, swimming back and forth between the Seaport District and Hull Bay.

That whale “breached behind the federal courthouse,” LaCasse said.


“It was, quite honestly, a lot of fun,” he said.

Wednesday’s sighting was somewhat unusual, said LaCasse, given the time of year, but Aquarium officials weren’t too concerned about the whale’s location close to the shore since the boating season is over for the winter.

“There are not as many recreational boats out there,” he said.

In late December, a juvenile humpback whale was also seen splashing deep into Rhode Island’s Narragansett Bay. The whale breached the surface of the water near the Mount Hope Bridge.

There have been a number of sightings “in strange places, all throughout New England,” said LaCasse.

Steve Annear can be reached at steve.annear@globe.com. Follow him on Twitter @steveannear.