A firefighter has been praised for rescuing a 14-year-old Tokoroa boy who sank up to his armpits in mud at Lake Moananui.

Senior firefighter Paul Carter stripped down to his underwear and T-shirt and went to the aid of Piri Tautari at 5.21pm yesterday, Fairfax media reports.

The lake has been drained to control the weeds, leaving fishermen to battle the wet mud to get to the water.

Piri, a Tokoroa High School pupil, was alone on a fishing trip and without a cellphone when he sank about 15 metres from the normal lake shore.

"He had sunk as far as he could go," Mr Carter told Fairfax.

Carter, along with other firefighters, slid out a stretcher which Piri grabbed on to.

"It was quick," Piri told Fairfax. "It took about five minutes to sink and I made it worse by wriggling. I was angry with myself for getting myself stuck. It was just stupid."

It took about 20 minutes to rescue him, and his boots stayed on the whole time.

Piri doesn't know who called the fire service, but he says he is extremely grateful to everyone who involved in his rescue.