Fog may have helped confuse a driver in Petaluma Tuesday morning who mistakenly drove into the water at the Petaluma marina, police reported.

"It was very foggy and the driver thought the road continued all the way around the Sheraton Hotel. He was trying to make a delivery to a business there when he just drove right into the water," said Petaluma Officer Art Farinha.

The silver Toyota Sienna was slightly submerged when he came to a stop. But it soon became worse.

"At first the water was only up to the wheel height, but the water was rising quickly and within 40 minutes it was up to the window of the van," the officer said.

Police were called at about 7:15 a.m.

"It happens from time to time. Usually it is someone trying to get rid of the car for insurance purposes. Fortunately they (the marina office) had waders and I didn't have to swim," said tow truck driver Tom Miller with Downtown Towing.

At the nearby coffee shop, The Marina Bean, owner Mike Symanski said it's not so unusual for a car to end up in water.

"The same thing happened four months ago. A man was putting his boat in with his truck and he didn't put it in park and it rolled back into the water. There have been four or five in the almost four years I've been here."

The name of the driver wasn't available.