British tourists had a lucky escape during a whale-watching trip in California when a 40-ton humpback whale leapt of the water and landed down on top of their kayak.

Tom Mustill and Charlotte Kinloch were paddling off Monterey Bay when a whale breached and came crashing down onto their boat, dragging them and the kayak under water.

The video above, recorded by a passenger on a whale-watching boat, shows the terrifying moment the whale hit the kayak, an experience Charlotte, 30, described as “like being in an avalanche”.

“It felt like being in an avalance, like a bus landing on us,” she told The Telegraph.

Remarkably, the pair escaped unharmed, with the only damage being a small dent in the kayak’s bow.

Tom Mustill and Charlotte Kinloch cling onto their upturned kayak after the whale encounter.

As the giant creature rose above the kayak, wildlife film-maker Tom thought it was the end for him and his friend.

“I remember coming to the surface and thinking, ‘How am I not dead? Maybe I’ve got lots of injuries but I’m in shock and can’t feel them’,” he told The Telegraph.

“Then I saw Charlotte and thought, ‘How is she not dead?"

The pair clung on to their upturned kayak until fellow paddlers came to ferry them to safety.

Tom Mustill and Charlotte Kinloch are rescued from the waters by fellow kayakers.

The captain of the whale-watching boat from which the video was taken, operated by Sanctuary Cruises, said he was amazed they were unharmed.

“This was one of the more dangerous situations that I’ve seen out here,” said Captain Michael Sack. “I’m not sure if at this point these two know how lucky they were.”

Photo credits: Sanctuary Cruises