A 20-year-old man has died at Parnell Baths in Auckland.

A dozen members of an Auckland family gathered at the city's Parnell Baths on Saturday evening after a young man died in a suspected drowning.

They stood sobbing and hugging each other as police spoke to them about his death.

"We are trying to work out how to tell his grandparents," a member of the family said.

Emergency services were called to Parnell Baths just before 7.30pm on Saturday.

Ambulance crews tried to revive the man, but were unsuccessful.

"It was a stressful and upsetting time for the friends at the scene," said a police spokesman.

The man's body was later transferred to Auckland City Hospital to undergo an autopsy.

It is believed he drowned, and another police officer at the scene said it was suspected a pre-existing medical condition could be to blame.

He said the incident had been referred to the Coroner, who would be responsible for ultimately ruling on the man's cause of death.

Parnell Baths is an Auckland City Council-owned facility and is run by Community Leisure Management, which runs 16 pools across the country.

CLM manager Craig Carter said members of the pool's staff were still processing what had happened.

"We are still working with police at this stage and cannot comment further," he said.