Police have rescued a group of 31 hikers stranded by a flooded river in Tasmania's central highlands, reports the Australian Associated Press (AAP).

The group, from the Seventh-day Adventist Pathfinder Club, had become stranded on the eastern side of the Fisher River, south of Devonport, police said.

Aged from 10 to 63, they had been camping in the Lake McKenzie area but heavy rain caused the Fisher River to rise, preventing them from leaving.

Police were notified in the late afternoon of March 8, and in the evening members of the northern police search and rescue squad arrived at Lake McKenzie with a Zodiac inflatable dinghy.

They then ferried the hikers about 500 metres across the Lake McKenzie in small groups. "Weather conditions were poor. The group members' clothing and equipment were saturated and several members of the Pathfinder group were extremely cold and believed to be at risk of suffering hypothermia," Tasmania Police Sergeant Andrew O'Dwyer said.

"One youth was subsequently treated by ambulance officers near Mole Creek for suspected hypothermia. He was not admitted to hospital."

Tasmanian Seventh Day Adventist communications director Wayne Boehm said the club, which comprises young people from across the state, was on its yearly bushwalking expedition.

The group spent the long weekend camping near Lake McKenzie. "We were caught out by the elements, there were no kids lost, we were just stuck on one side of the river," Mr Boehm said.

"All the kids arrived home safely ... there was one child that was suspected to have hypothermia, but he checked out all OK. "They were all back at school today," he said.