Two giant sperm whales stunned tourists aboard a boat off Newport Beach.

Holidaymakers erupted in cheers as the colossal pair swam gracefully near their vessel in California on September 17.

The sea mammals, each measuring around 60ft (18m), surfaced dramatically, their massive tails lobtailing above the waves.

The group said that they had received a tip from fellow captains at Dana Wharf Whale Watching about two whales cruising through the area.

The crew then scanned the horizon and lowered a hydrophone into the water to detect the whales' distinctive clicking sounds, known as codas, which helped them track the giants.

One tourist said: 'We were able to observe the whales for more than five hours and stayed with them until the sun began to set.'

Sperm whales are instantly recognisable by their angled blowholes and wrinkled skin. They are the largest toothed whales in the world, with males weighing up to 50 tonnes.

These deep-diving predators can plunge for over 90 minutes, reaching depths of more than 4,000ft (1,219m) in pursuit of giant squid.

Though they occasionally pass by Newport Beach, such sightings remain rare and unpredictable.