ATHENS, Greece (AP) — A 24-hour strike by seamen has left Greek ferries and other passenger boats tied up in port, stranding tourists and Greeks heading for vacation and leaving many islands cut off for the day.

The PNO seamen's union called Wednesday's strike to demand salary increases as part of collective wage agreements. Dozens of inhabited Greek islands don't have airports and are accessible only by sea.

The passenger shipping business association SEEN, with which the seamen's union had been negotiating, had expressed surprise when the strike was announced in late June, saying it offered a 2% wage increase for 2019 on top of a retroactive 2% increase for 2018.

It said the offer, along with staff increases, was "beyond our actual capabilities during a particularly difficult time" with 50% fuel cost increases.