Wombat foraging in the ocean on Tasmania's north-west coast has left experts guessing as to the cause.

US tourists Chaz and Bee Taylor stumbled upon the novel moment after a hike near Bluff Hill Point last February.

"We really didn't know what a wombat looked like exactly, so that delighted us," Ms Taylor said.

"We come from Montana and we have a lot of bears, so to us this looked like a little friendly bear."

Mr Taylor said he was surprised to see it wander into the ocean, so he sent the footage to the Wombat Protection Society of Australia (WPSA).

"It's very much a land animal — most animals you don't see do that," Mr Taylor said.

"We just wanted to find out whether this was an odd thing or not."

'Another layer to the uniqueness of wombats'

WPSA Victorian director Jennifer Mattingley has run a wildlife rescue service for three decades, but said it was the first time she'd ever seen a wombat behave that way.

"We were really grateful that they've sent [the video] in because to us it's unusual behaviour," Ms Mattingley said.

"We've seen photos of footprints on the sand on the beaches, and they might go right up to the water's edge, but we've never ever seen that sort of behaviour.

"There was quite a lot of people in Tasmania saying they had seen this behaviour, which probably makes us think if they're coastal wombats it isn't that unusual for them."

Ms Mattingley said while she had never seen a wombat in the ocean before, she had previously received reports of wombats near Tidal River, on Victoria's south coast, in freshwater that runs into the ocean.

The nocturnal animals are an uncommon sight in the wild, rarely appearing during the day.

Ms Mattingley said when wombats were seen during the day, often they were sick with mange.

However she said she didn't believe this wombat appeared infested. 

"Their habitat is decreasing, we're sort of moving in on their areas, so perhaps we are seeing a bit more of them than we did a few years ago," she said.

"But there's so much about them that we don't know.

"It's just adding another layer to the uniqueness of wombats." 

'Particularly unusual' behaviour, researcher says:

Professor Scott Carver, a former-University of Tasmania wildlife ecologist who now resides in the United States, has spent much of his time in the state studying wombats.

He said while wombats have been known to swim in water occasionally, he'd never heard of any evidence of wombats swimming in the ocean before.

"It was interesting that it seemed to be drinking, which is, I think, particularly unusual," Professor Carver said.

"Wombats are definitely known to wander around on the beach and forage around in those areas.

"I have seen one that's feeding on salt marsh plants before in coastal areas, like samphire — I haven't seen them feeding on seaweed, which this one was doing."

Without further research, he said it was impossible to know what drew the wombat down to the water but speculated it could have been health related.

"There are lots of cases of animals that will actually go and try and deliberately acquire things like salts and other minerals," he said.

"Things like salt may be somewhat limiting in the diet for a wombat.

"It definitely occurs in nature and so that's why I think that this is a plausible explanation for perhaps what we're seeing with this wombat's behaviour."