The startling moment a pod of killer whales surrounded an inflatable boat has been captured on camera in a terrifying but thrilling video.

The clip above shows the moment wild orcas swam directly under the tiny boat near Los Angeles last week.

During the footage, one of the crew is heard screaming: "We got to go, they're under our boat".

The person who filmed the video, who has worked on the Southern California Killer Whale project since 1984, later wrote online: “These wild Orcas that I have known for many years now came over to my 10-foot inflatable maybe just to say hello.”

But experts say the people who were surrounded by whales were "lucky" and should not have been threatened by their "simple curiosity".

Vassili Papastavrou, whale biologist for the International Fund for Animal Welfare (IFAW), examined the footage and said: "The people who experienced this behaviour were very lucky.

"The orcas that are spyhopping are looking into the boat. Orcas have reasonably good above water vision."

The whale expert said anyone in this situation should not start a boat engine as the unexpected revving of the engine might result in an orca being injured, or less likely the boat hitting an orca resulting in injury to people in the boat. 

"When in the company of whales, it is good general advice to allow the animals to control the nature and duration of the interaction," he said.

"Orcas are extremely sophisticated predators.  In different parts of the world they eat different species (from various fish to other marine mammals, including whales) but they are not recorded as eating people."

Apparently sperm whales sometimes will stop what they are doing and behave in a similar way to these orcas.

"However, sperm whales are much less manoeuvrable and there is more of a danger of them getting flustered, bumping into each other and then hitting the boat, which I have experienced," Papastavrou added.

Naomi Rose, killer whale biologist at the Animal Welfare Institute (AWI) in Washington, said: "In my opinion, what this video captures is simple curiosity.

"These are transient killer whales, which means they are mammal-eaters. From their behavior, they were sated - probably made a kill recently - but curious about the dinghy and the people in it. They possibly they liked the sound of the motor, as they appeared to be responding to it in some way with those raspberry-like burbles at the surface – killer whales don’t usually vocalise at the surface that way, but when they do, this is the most commonly heard sound.

"Generally speaking orcas – whether fish eating or mammal eating – avoid humans in the water and approach boats only when the boats are moving at speed, so the whales can play in the wake or near the bow.

"There are a couple of populations that are known to approach divers and boats more readily, but these are the exception to the rule.

"For transients to approach a stationary, small dinghy like this in completely still water is unusual and to be honest, a bit nerve-racking.

"The dinghy is unusually small and again, that combined with the motor may have simply attracted them for some reason."

How would you feel if you were surrounded by killer whales while in an inflatable boat? Let us know in the Comments section below.

Video credit: Newsflare