Search and rescue are looking for a young person who has been swept down a river in Fiordland.

Emergency services were called about 11.40am after being alerted to an individual being swept down the Hollyford River, near Lower Hollyford Road.

A police spokesperson said officers and Search and Rescue teams were in pursuit and that a helicopter had been deployed.

Hollyford River is described by NZ Fishing as being "off the beaten track". The terrain is rugged and remote.

The group described the upper reaches of the river as rough.

The "very, very cold" water can appear shallow and sedate below Hidden Falls, but is often much deeper and more powerful than it seems, NZ Fishing said.

Main image (RNZ/Photo 123rf.com): The Hollyford River in Fiordland.