ATHENS, Greece (AP) — Greek ferry companies are urging crews to call off a planned Sept. 3 strike, saying it will leave nearly 200,000 travelers stranded during the busy tourism season with no alternative means of transport.

The PNO seamen’s federation is seeking salary increases and tax breaks. PNO has threatened to extend its 24-hour strike, which will affect all routes to Greek islands including popular destinations such as Mykonos.

Ferry companies said Tuesday that 180,000 people have booked to travel by ferry on the day of the strike. They said in a statement that due to the busy season operators will be unable to reschedule their ferry timetables, and warned that tourists trapped on islands will miss their flights home.

Tourism is a key earner in Greece, with record arrivals expected this year.