A boy who tried to save a capsized kayak ended up stranded in raging floodwaters near Houston, dramatic video shows.

Local resident Heidi Hall saw the boy and a companion trying to retrieve the kayak before he got swept up in the roaring rapids on Sunday, Caters News reported.

The youngster struggled to keep his head above the water in Lake Woodlands, 39 miles north of Houston, as he held onto a submerged buoy line.

Rescuers finally managed to pull the boy out danger and covered him in a blanket to cheers from onlookers.

“I couldn’t believe these two kids went after the kayak,” Hall said. “The current was obviously really strong but they swam out anyway.

“One of them managed to get to the shore but this kid was stuck for about 20 minutes just holding on to the buoy line,” she said. “All of the major rescue teams are downtown so this group didn’t have time to wait for a boat to appear.

“He could have lost his life just for the sake of a kayak,” she added.