A boat has come off a moving trailer during peak hour traffic coming to rest in the middle of a Mount Maunganui roundabout.

A police spokeswoman said the vessel fell off a trailer in the northbound lane of the Bayfair Roundabout on Maunganui Rd about 4.50pm yesterday.

Although there were no people in the boat at the time of the incident, there was a dog, she said.

Janine Durham-Westhead was driving behind the trailer when the boat fell off and said she could "see it about to happen" before it did.

The boat slid off a trailer on to the road. Photo / Supplied
The boat slid off a trailer on to the road. Photo / Supplied

"To us it looked like the boat was just sitting on the trailer and not tied down... as they approached the roundabout it just slid off."

She said she backed off from the vehicle moments before as it looked like it was going to come off.

The roundabout was instantly down to one lane, with people rushing over to try and help load the vessel back on and get it off the road, she said.

A police spokeswoman said the incident had caused a bit of congestion at the time but the scene had been cleared within 20 minutes.

Photos shared on local traffic pages showed the dog in the boat, who did not appear to be injured.