The ferry between Halifax and Alderney Landing in Dartmouth is not running at the moment.
Transit officials are moving buses to both terminals to shuttle people across the harbour.
HRM says the problem with the ferry is mechanical and not serious.
Another ferry is currently being warmed up and ferry service should return shortly. At that point, bus service will be cancelled.
HRM spokesperson Brendan Elliott is not sure whether the repairs will be finished in time to allow for regular 15-minute service during the afternoon rush hour.