A mechanical engineer from California filmed herself while snorkeling with a whale shark in La Paz, Mexico.

Anna Harris, 22, is bikini-clad when she saw the whale shark off the coast of Mexico.

'Swimming with the whale sharks was an incredible experience,' she told Caters News.

'It was daunting when I first got into the water and saw a 30-foot shark gliding through the water right in front of me, but they are so docile and calm that it was peaceful swimming alongside them,' she added.

'Even though it's a filter feeder, when you're 5-foot-3 and the whale shark is 30 feet long, it's pretty startling.'

Whale sharks are the largest fish in the sea reaching lengths of 40 feet or more. They feed on planktons and are filter feeders.

These animals prefer warm waters, populating tropical seas. Although massive, whale sharks are docile fish and sometimes allow swimmers to hitch a ride.