Police would like to hear from anyone who witnessed a jet-skier getting into difficulty on the Waimakariri River, north Canterbury yesterday.
The man was rescued from the water by helicopter and taken to hospital where he later died.
"Police are grateful to members of the public who assisted at the scene, along with local surf lifesavers and the Coastguard," police said in a statement.
"We are seeking information and video or photographs from anyone who was at Kairaki Beach before, during or after the rescue around 1pm."
Anyone who can help is asked to call Waimakariri Police on 03 363 7400.