A fisherman has filmed his terrifying encounter with a great white shark just a kilometre from one of Adelaide’s most popular beaches.

Video captured by Matt Robertson shows the six-metre shark circling the small fishing boat, and nudging its motor, off Semaphore Beach about 9am today.

“It’s a f—king great white, oh my god!’ Mr Robertson, who was aboard the boat with his father, can be heard saying.

“So glad I didn’t get into the water before,” he adds.

For several minutes, the large predator circled the vessel, before retreating into deeper water.

Beachgoers told 9NEWS they were shocked the nail-biting encounter unfolded so close to the swimming hot-spot.

“We're going to get this beach packed tonight, so pretty scary for everyone,” one swimmer said.

This morning’s incident is the latest in a series of encounters in South Australian waters.

Earlier this week, a five-metre great white circled a fishing boat near Port Victoria, on the Yorke Peninsula.

This year has seen a dramatic surge in the number of shark sightings along the state’s coast, with 139 reports in 2017- the highest number in four years.

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