A man has been found dead in the water alongside his two still-living companions after spending about four hours in the sea off the coast of Geraldton in Western Australia.

Police were alerted at 2.25pm on Sunday after a boatie came across the trio after their boat had been hit by a wave about two nautical miles northwest of the Batavia Coast Boat Harbour.

A marine rescue squad was deployed from DFES Marine Rescue Geraldton with the civilian vessel intercepted late in the afternoon.

Emergency services met the rescuers as they returned to harbour with the two survivors taken to Geraldton Regional Hospital for treatment for suspected hypothermia.

The deceased man, believed to be in his 60s, is thought to be a Geraldton area local.