Parks Canada says the Cabot Trail is closed between Ingonish and Neil’s Harbour because of flooding caused by heavy rain, overnight.
The federal agency says a section of the Cabot Trail in the Black Brook area has been washed out.
It says work is underway to repair the washout and a road crew is carrying out a full assessment of the road along South Mountain.
Parks Canada says the road could be reopened to traffic by this evening if no major problems are found during the road assessment.
However, it also warns large sections of the road could be reduced to one lane.