A kayaker who got into trouble in rough seas off the Canterbury coast last night was "extremely lucky" to escape with his life, rescuers say.

The man activated his locator beacon about 4km offshore from Motunau Beach in North Canterbury.

The Christchurch-based Westpac Rescue used night vision goggles, and help from local fishing vessel Navigator, to find the kayak in strong offshore winds and rough seas.

He was returned to shore where he was checked out by chopper paramedics.