A female tourist has died after being swept off rocks and into the sea in Sydney's southeast.

It's believed the woman, understood to be 25, was posing for a photo on the rocks at Bare Island, off La Perouse, when she was swept into the water about 3.35pm, police said.

A search and rescue operation was begun after the incident was reported.

Police at the scene. (9NEWS)

Emergency services, including police boats and divers scoured the area around the rocks and further out to sea.

They later discovered her body.

Divers and police boats were dispatched to find the woman. (9NEWS)

It is believed the woman's family were at the scene when she was knocked into the water.