A teenager is missing, presumed drowned, after he was washed off his boogie board at Piha yesterday.

The tearful father and sister of the boy, believed to be 15, comforted each other at the Piha Surf Lifesaving Club last night.

Surf lifesavers began searching about 3pm, after a boogie board washed onto the shore.

Club captain Tony Featherston said their concerns were confirmed when friends of the teenager told lifeguards their mate was missing.

"We just kept searching until we had it confirmed, and then we went all-out."

Mr Featherston said up to five boat crews, a jet ski crew, a Westpac helicopter and the coastguard plane looked for the teenager.

He said it was always difficult when a person went missing, presumed drowned.

"The guards will be upset. But that's nothing [compared] to the family. Someone's lost a son, a brother or a mate, and that's hard."