Firefighters are tackling a boat ablaze near the Folly Inn in Whippingham.
Crews have been alerted by HM Coastguard.
Cowes RNLI have also been called.
The vessel is said to be located in the sea just off the Folly Inn pub in Whippingham.
UPDATED 5.39PM
The fire is now out.
No one is reported to have been hurt, the fire service said.
Two appliances from Newport were called.
A spokesperson for HM Coastguard said:
"The Coastguard received a called at around 4:45pm this afternoon reporting a small fire on a motor boat on the River Medina, Isle of Wight.
"Cowes Lifeboat and Isle of Wight Fire Service were sent to the incident to help. All people on board are reported as safe and well and the boat is now secured, and the fire is out."