A young man who apparently drank too much at a party fell up to 15m down a Waikato River bank after going outside to be sick.
Emergency services were called to River Rd in Queenwood, Hamilton, about 11pm.
Senior Sergeant Tim Anderson said the 26-year-old man, who had been at a party late last night, appeared to have "felt the need to go outside and be sick".
"It looks like he has gone one tree too far and fallen down a 10-15m bank and seriously injured himself."
Firefighters used a rescue stretcher to recover a man and get him to a police rescue boat. He was then taken to a waiting ambulance for treatment.
Mr Anderson said police were pleased with the result. However, police were questioning whether an over-indulgence in alcohol had led to the incident.
"Each week now Hamilton emergency services are attending a variety of incidents on the Waikato River involving either a degree of tragedy or people needing help," Mr Anderson said.
"People involved in activities on, in or near the river are asked to be mindful of this so we can prevent further incidents like last night's."