A Malaysian student has saved a woman from drowning off southeast Queensland and likely lost his own life in the process.

Police said the 25-year-old man went missing off Moreton Island after helping a woman in difficulty shortly before 4 p.m. (AEST) yesterday.

The pair were with a group of Malaysian students from the University of Queensland camping at Honeymoon Bay with Brisbane-based Blue Planet Tours, said Trevor Hassard from Moreton Island's Tangalooma Wild Dolphin Resort.

The group went swimming in the bay and soon found themselves caught in a rip.

"As they came out past the rocks, they were yelling and screaming,'' Hassard said.

"The Malaysians who made it to the rocks leaned over and grabbed the people as they went past and they were very successful,'' he said.

"They got down to two people left, a male and a female in the water and the man was within reach," Hassard said. "But he actually grabbed the female who was out of reach and pushed her towards the people who were rescuing other members of the group."

"She got pulled out of the water but in pushing her within reach, he pushed himself out of reach.

"He saved her life but it is likely that he lost his own," he said. "It was absolutely amazing - a totally selfless thing.''

Hassard said people had been lost at Honeymoon Bay in the past.

Conditions there varied so people staying at the resort were advised not to swim there.

"We have a policy where no one is allowed in the water past their knees at Honeymoon Bay,'' he said.

Police are talking to Blue Planet Tours to determine what happened.

Its manager, Ian Stuart, said the company had been "devastated'' by yesterday's events but declined to comment further.

An air and sea search was due to resume at first light tomorrow.