NEWPORT BEACH, Calif. (KSWB) – Two giant gray whales thrilled a tour group with their up-close antics off the coast of Southern California last week, bobbing, rolling, and even flashing their tails within a few feet of the small raft.

Experts call the behavior “mugging,” and it displays the kind of gentle curiosity that has earned the species the nickname “friendly whales.” The length and proximity of the encounter, which happened Thursday evening off the coast of Newport Beach, excited even veterans at the whale watching company that organized the tour.

Jessica Roame, who leads education programs for Newport Coastal Adventure, called it one of the company’s “most epic gray whale encounters of all time.” Roame emailed Nexstar’s KSWB to share videos and explain what happened.

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Clips recorded on cell phones show the massive creatures bobbing just below the surface alongside a small “fast raft” vessel holding about 15 people. Whale-watchers gasp and giggle as the whales blow from their blowholes, hold their heads above water, and calmly lull from side to side.

At one point, one of the whales lifts its tail in the air, looking as if it might splash back down right in front of the raft. “Splash us,” someone on the boat excitedly says. But the tail angles away from the boat as it chops back down into the water.

Roame said the tour group floated alongside the whales for more than 45 minutes. She emphasized that the raft’s engines were powered off and that the tour guide kept their distance until the creatures approached them, drifting at sea. It also helped that the vessel was one of the only boats on the water at the time.

“Boaters should always be respectful, and move slow when a whale is spotted, and keep your distance,” she wrote. “Occasionally, if you are respectful, with engines off, these whales will approach boaters on their own accord like these two did, to check us out.”

Roame said gray whales, which can reach lengths of up to 49 feet and weigh as much as 60,000 pounds, are migrating north during March. The whales’ long journey extends from their breeding waters in Mexico back home to Alaska, passing California’s coast.

“It’s important to stress that during this time in the year, boaters should be cautious … and keep a sharp eye out for migrating gray whales, because they are on the move all along the coast right now,” she wrote.

While whale watching season affords plenty of opportunities to catch a glimpse of the creatures, Roame described an up-close encounter like Thursday’s as “very rare.”