Coastguard North Canterbury volunteers have joined a multi-agency search for a man swept away in the Cass River near Craigieburn Forest Park.

The man had been walking the Cass-Lagoon Saddle Track with a companion on Thursday when both fell into the river.

One of the men managed to reach the riverbank, but the other was swept further downstream.

Police requested Coastguard North Canterbury’s assistance shortly after 2pm, with the search focused on a section of the river about four to five kilometres upstream from the State Highway 73 bridge.

The man who reached the bank then faced an hour-long journey through rugged native forest and across a rock-strewn riverbed before finding a member of the public, who raised the alarm.

He was later taken to Christchurch Hospital for medical treatment.

As darkness approached, Police, Land Search and Rescue, the Westpac Rescue Helicopter and Coastguard North Canterbury searched for the missing man.

Coastguard’s Swift Water Rescue Team was sent to the scene, along with the rescue vessel Blackwell Rescue.

Six Coastguard North Canterbury volunteers took part, with three searching from the vessel and the others working along the riverbank.

During the operation, Coastguard volunteers found a beanie believed to belong to the missing man, helping search teams narrow the area they needed to cover.

Crews faced fast-moving water, steep forested terrain and fading light during the search.

Coastguard North Canterbury thanked the volunteers who responded at short notice, as well as the member of the public who helped raise the alarm.