Maybe it was looking for Deer Island.
Passengers on a commuter ferry trip from Hingham to Rowe’s Wharf were greeted by an unusual sight early Thursday morning: a deer swimming past the vessel and toward one of the Boston Harbor Islands.
Jessica Bartlett, a reporter with the Boston Business Journal, captured video of a portion of the seafaring animal’s voyage, after the captain of the MBTA ferry pointed out the deer on the boat’s starboard side.
“On today’s @MBTAferry a (rein)deer was seen swimming to one of the islands!’’ Bartlett tweeted. “Didn’t know deer could swim!’’
The short clip shows the back of the deer’s head as the animal paddles, bobbing up and down with the waves. The encounter was fleeting, as the 7:15 a.m. ship continued on its journey through Hingham Bay toward the city’s port.
In a follow-up e-mail, Bartlett said the captain took to the intercom to urge passengers to look outside at the “pretty big’’ deer swimming to what she believed was Grape Island, a 101-acre spot in Hingham Bay that’s known for its “abundance of wild berries . . . that provide food for the local wildlife,’’ according to the Boston Harbor Islands’ website.
Grape Island is located off Weymouth and Hingham, but is part of the Boston Harbor Islands National Recreation Area.
Bartlett said she’s unsure if the deer made it to land safely, having lost sight of it once the boat went by.
“But he was certainly hoofing it,’’ she said.
Those on board the ship cracked a few jokes about what they’d seen.
“One of the passengers joked that it must be a reindeer,’’ she said. “Another passenger said it looked like a six-point buck.’’
While certainly a strange sight to behold — perhaps especially so this close to the Christmas holiday — deer are actually strong swimmers, said Marion Larson, a spokeswoman for the state Division of Fisheries and Wildlife, and they can move far and fast in the water.
“They are swimmers,’’ she said, “and they do go from one place to another sometimes by swimming.’’
According to the National Parks Service, Deer Island, another of the Harbor Islands, allegedly got its name centuries ago due to the deer that swam there from the mainland to escape predators.
Larson said it wasn’t clear how abundant the deer population is on some of the islands nowadays, but officials have seen deer tracks on Grape Island before.
“Given distances, it would not be a surprise to have deer on the islands,’’ she said.
In November, a group of Maine lobstermen came to the aid of a young deer they found swimming five miles off shore, after it apparently got caught in a strong current. The group brought the deer onboard then released it closer to land, a rescue mission they documented online.