Lorraine Aitken was walking along Pambula Beach on Monday morning, November 20, when she stumbled across one of the fascinating creatures.

Unfortunately it was not in a good way, with Lorraine saying it was clearly dying, and perhaps not from just being washed up on the sand.

"It had a small puncture wound on its back where it looks like something may have tried taking a bite of it," she said.

The sea snakes are highly venomous and typically found in tropical waters throughout most of the world's oceans.

"I walk on the beach every day and I've never seen one like this before," Lorraine said.

"The lady at National Parks in Merimbula called me back and said she's not heard of one in 20 years of working here."

Dr Christina Zdenek from University of Queensland's School of the Environment said it was "definitely unusual" to see a yellow-bellied sea snake this far south.

"Their range typically doesn't extend further south than around Brisbane - in tropical waters," Dr Zdenek told ACM.

Pambula is around 1500km south of Brisbane.

"I suspect it's due to extreme weather out at sea or a storm surge [washing it ashore that far south].

"It's often the case that they are struggling already and if they have slowed down they they can be subject to predation."

Dr Zdenek said Australia had 37 species of sea snake, more than any other region in the world.

"The yellow-bellied sea snake is the only one we know of that hunts from the surface - it will sit on the surface and ambush its prey," she said.

"They are also know to create a 'slick' with hundreds of snakes all together in one big group on the surface of the water.

"We don't know exactly why they do it, but one cool idea is that the slick creates a patch of shade, and fish get curious about the shade and swim closer, so all the snakes then feed together."

While the yellow-bellied sea snake - like all sea snakes - was highly venomous, Dr Zdenek said they were typically "very docile" when in the water.

"They are curious if anything, swimming up to divers to check out reflections in their goggles and then swimming away.

"When conflict occurs is when they are hauled up in trawler nets."

Dr Zdenek said the bright yellow colouring was a warning to predators about their toxic nature. She said they were also known to be poisonous to birds if eaten.

"They are highly evolved for a life at sea. They are the only pelagic sea snake."