A man is missing after a boat sank on Lake Rotorua, leaving five people in the water.

Rotorua Police were advised of a group in distress at about 5.45pm. Police received calls from concerned Ngongotaha residents reporting what appeared to be a boat in trouble.

A resident responded to the emergency, going out in his own vessel. He discovered a group of five men in the water after their boat had been swamped and sunk.

The resident rescued four, but the remaining man could not be located.

Coastguard were deployed and two Coastguard boats spent the remaining daylight hours searching the area where the missing man was last seen.

The others were all taken to Rotorua Hospital by ambulance and treated for hypothermia.

The search for the missing man has been suspended for the night and will resume tomorrow morning.