The body was recovered following a multi-agency search for a male passenger whose car submerged in water. (ABC News)

Emergency services have located the body of a male passenger after a car submerged underwater at the Royal National Park in Sydney’s south.

Authorities were called to Audley Weir in the park about 1:15am, following reports a car had gone into the water with two people inside.

The 20-year-old male driver was able to get out of the vehicle, but the passenger, believed to be in his early 20s, became trapped.

A police dive squad was deployed and a blue car was retrieved just before 11am on Wednesday.

Acting Inspector Steven Planinic from the Traffic and Highway Patrol Command confirmed the man’s body was retrieved by police divers.

He is yet to be formally identified.

Driver in custody

“The driver of the vehicle … was subject to mandatory testing and has been released from hospital, where he is now in custody at Sutherland Police Station, taking part in a police interview,” Acting Inspector Planinic said.

Police said a second vehicle was involved in the incident, and its driver, 18, was also speaking with investigators.

“It does not appear at this early stage to be any contact between the two vehicles,” Acting Inspector Planinic said.

He said one potential theory police were investigating was whether racing was involved.

A mechanical examination of the blue vehicle was expected to take place, Acting Inspector Planinic said.

NSW Police said there were initial delays to the multi-agency search due to low night-time visibility.