North Shore fire officials say some quick-thinking strangers revived and saved the life of a young man out for a swim in Lynn Canyon.

Asst. Chief Jeremy Duncan, with North Vancouver District Fire and Rescue Services, told CTV News Vancouver his team responded to the waters near Twin Falls on Monday around 4 p.m. when they got a call about a possible drowning.

When fire crews, along with park rangers and paramedics, arrived at the gravel beach just below the falls, the 24-year-old was breathing and coherent, when just moments earlier, he'd been unconscious.

Duncan credits a couple and a family, both out enjoying Lynn Canyon Park, for noticing that something wasn't right, and for getting in the water to pull the drowning swimmer out.

"When the family was able to pull him out to the river's edge, he was pulseless and not breathing," said Duncan, who explained the family gave the swimmer CPR for about two minutes, before he coughed up water and was revived.

Over a dozen first responders used a stretcher and rigged a pulley system to help raise the injured man up the trails and steep slope to a waiting ambulance, where he was taken to hospital in serious condition.

On Tuesday, officials with Vancouver Coast health called his condition "stable."

At the spot of the near-drowning, Bruce and Leah Dayton - who were enjoying the summer sunshine with their four sons on Tuesday - expressed awe.

"That's amazing. A lot of people wouldn't do that. But to jump in and do that it's pretty cool," Bruce said.

Over the past 30 years, dozens have people have died or have been seriously injured in Lynn Canyon, many while cliff jumping.

Last September, first responders launched a full-scale tactical rescue to save a woman who slipped and fell while cliff jumping and had to be hoisted 50 metres to the iconic suspension bridge in a full-body cast.

And while fire officials say there's no indication the swimmer involved in this took any risks, Duncan says it's a reminder that in this patch of wilderness, there a lot of hazards you can't always see, like strong currents, and rocks and debris lurking below the surface.

"Come prepared. Make sure you have the proper footwear. Make sure that you can swim (in) these conditions," Duncan said.