The family of a man believed to have been swept out to sea near Greymouth in March have posted a $30,000 reward for information that leads to the recovery of his body.

Zarn Murphy was last captured on CCTV arriving at a house in Cobden, Greymouth, about 5pm on March 6 to collect his kayak, according to a post on Facebook by his nephew Caleb Hunt.

“He had intended to paddle across to the fishing boat he worked on at the Blaketown side of the wharf via the Cobden lagoon, something he had done many times before without incident,” Hunt wrote.

The following day, around 5pm a person walking along Blaketown Beach saw what appeared to be Murphy washed up on the beach near the end of Robinson St, Hunt said.

His kayak and paddle were located nearby, about 500m south of the Blaketown tip.