A 19-year-old is feared drowned after he disappeared while swimming in the Ruamahanga River near Opaki just north of Masterton.
Police said it appears he was swimming with a group when he failed to surface just after 5pm on Monday.
Ambulance staff, fire crews and police scoured the shoreline, while the Westpac Rescue Helicopter searched from the air.
The police dive squad will search deeper pools in the river on Tuesday.
