A man suffering from hypothermia has been found on a yacht which was floating adrift in the Riverside area of Norwich on Saturday afternoon.
Police were called to reports of a small yacht, called Vagabond, which was unmoored and drifting in the water.
They discovered a 19-year-old man on board, soaking wet, drunk and suffering from hypothermia.
No other people were onboard.
The man was taken to the Norfolk and Norwich University Hospital. His condition was described as stable.
Officers are making enquiries into the circumstances and a police cordon had been put in place on the boat which is now moored up in the area.