Officers were called to Swanwick Marina at 11.15am today by the ambulance service.
It followed reports a man had died at the scene.
Officers attended and confirmed a man in his 50s from Wales had died.
READ MORE:Â Man in his 50s dies at city centre square
A file will be prepared for the coroner. It comes a day after a man in his 50s died at Guildhall Square following a medical emergency.
A team of a doctor and a specialist paramedic was deployed to the incident by helicopter, Hampshire and Isle of Wight Air Ambulance confirmed.
The air ambulance landed in East Park just after 5.15pm opposite Solent University and doctors onboard joined three ambulances inside the cordon at the square.
