That's the advice that Irish Ferries is giving to Irish football supporters who may be planning to travel overland in support of Ireland's Euro 2012 bid.
According to the company, early indications are that an exodus of fans travelling to Poland and Ukraine in camper vans is expected and already bookings are being made.
With games fixed to overlap with the main summer travel season, fans are being urged to reserve their sailing dates before the rush gets under way.
Fans can choose between direct services to France and overland routes through the UK with the result that they benefit from the extra space available, even though certain sailings will fill up quickly, an Irish Ferries spokesman said.
Information on sailing dates and bookings can be had online at www.irishferries.com or by calling 0818 300 400.
