Police have no leads on the driver of a car that plunged off the Englishtown ferry into St. Anns Bay in Cape Breton earlier this week.

It happened so fast that witnesses have given police little to go on.

Police divers are using sonar to try to locate the submerged car.

RCMP said the car drove across the deck and over the upright ramp on Monday night.

Police said the small car was carried along by the strong current for about 200 metres, and then disappeared under the water. Witnesses were not able to get the licence plate number, or which province or state the car may have come from.

Divers scoured the fast moving channel near the ferry terminal on Tuesday.

At one point, an oil slick was spotted on the water.

Police said they are still not certain if the driver was alone in the vehicle.

No one has filed a missing person report in the area, RCMP Staff Sgt. Craig Yorke said.

"So far there isn't anyone reported as missing in Atlantic Canada. Also we’re sending out a bulletin to all the city police forces, just giving some sort of descriptors of a silver car, if anybody’s reported somebody missing driving a silver car who may have been in the Ingonish Beach area visiting or whatever. We’ll see where that will take us," he said.

"You have to think the person must be from another country if somebody hasn’t reported the individual missing, especially with all the media around this incident," he added.

Yorke said divers are continuing to search the channel. Search and rescue crews are keeping an eye on an ice floe that's headed into the channel where the search is taking place. That might disrupt the search, Yorke said.

The province's Department of Transportation has started an internal investigation into the incident.

Englishtown is located 61 kilometres northwest of Sydney.

The ferry runs across St. Anns Harbour connected to an underwater cable. It provides a shortcut to the Cabot Trail in northern Cape Breton.