Irvine harbours (Port Code:GBIRV) serving Irvine at Seagatefoot and Fullarton in North Ayrshire have had a long and complex history. Irvine's harbour was one of the most important ports in Scotland in the 16th century. Across from the main harbour at Fullarton on the River Irvine there was also terminal for the ICI-Nobel Explosives plant on the River Garnock. Much of the harbour went into decline in the 19th century when Glasgow, Greenock and Port Glasgow achieved higher prominence as sea ports. There was still some commercial sea traffic linked to local needs, though the harbour went into further terminal decline in the 20th century. The weir on the River Irvine forms the formal upper limit of the harbour.
Formerly owned by ICI, Irvine Harbour is now the property of NPL Estates who also own the Big Idea site, the Bridge of Scottish Invention, locally known as the 'Sliding bridge', and other land on the Ardeer peninsular. Irvine Harbour is now officially closed as a commercial port. Until recently NPL provided a slipway for dinghys, as well as moorings and berths for pleasure craft. However, silting has taken place and the Scottish Maritime Museum's berths are not for public use.