Caledonian MacBrayne ferry services have been cancelled after the Rail & Maritime union called staff out on strike in a dispute over the potential sale of the organisation.
Two thirds of ferry services on the west coast of Scotland have been suspended as a result.
The strike, which started at midnight and will last for 24 hours, follows two days of work to rule at the ferry company.
The dispute centres on a tendering process which could see Clyde and Hebrides routes operated by the state-owned company taken over by a private firm.
CalMac said it would operate nine of the usual 27 routes, on amended timetables, with 40 per cent of usual passenger capacity available.
The routes mainly affected will be those serviced by the company’s larger vessels including the Outer Hebrides, Mull, Colonsay, Coll, Tiree and Islay.
A number of the smaller routes that attract large numbers of passengers such as Iona will operate as normal.