Up to 800,000 people are on the move this weekend on trains, aeroplanes and buses for the Easter bank holiday.
Aer Rianta said as many as 260,000 passengers are due to travel through Dublin Airport, 50,000 through Shannon and 50,000 through Cork in the five days up to Easter Monday.
Iarnrod Eireann expects to carry at least 300,000 passengers and Bus Eireann 100,000 over the same period.
Motorists, meanwhile, face a weekend of delays and congestion, building up to Easter Monday when the worst traffic problems are expected.
The figures for air traffic are similar to last Easter, according to Aer Rianta spokesman Mr Flan Clune.
However, he said they disguise a significant drop in inbound traffic of 10-20 per cent, which was linked to the foot-and-mouth crisis, and a similar rise in outbound traffic.
"There has been a phenomenal increase this weekend in the number of people going on charter holidays to sun destinations like Spain, Portugal and the Canary Islands," he said.
"But the plus on that side is matched by a drop on the other. Traffic from the UK has fallen dramatically, and advanced bookings are looking bad."
He said business through the airports had been running 10 per cent ahead of 2000 levels until the foot-and-mouth crisis broke last month. The loss of St Patrick's Day, Cheltenham and rugby travellers had wiped out those gains, he said.
He added that a further drop in air traffic of about 20 per cent was expected this summer.
Among those enjoying a boom in bookings is Falcon/ JWT, which said it was flying more than 4,000 people this weekend to the Canary Islands, Majorca, Spain and Portugal - an increase of 8-10 per cent on last Easter.
"There is definitely a big increase in bookings," said a spokeswoman for the company. "We wouldn't see it as necessarily related to foot-and-mouth, because a lot of these people would have booked in advance. It's more to do with (a) the weather and (b) the fact that people have that bit more money."
Up to 300 charter flights - carrying an estimated 30,000 people - are due to depart from the State's three main airports over the weekend, an increase of 50 per cent on an ordinary weekend.
The exodus mirrors that in the UK where an estimated 2 million people have left on sun holidays this weekend.
Motorists faced another day of delays and tailbacks yesterday as people made their way home for the holiday.
AA Roadwatch said yesterday's traffic was as bad if not worse than Thursday's, with half-hour delays through many towns on primary routes.
Areas worst affected were the N7 through Kildare, the N4 through Enfield - where a 5 1/2mile tailback was reported - the N6 through Loughrea and the N1 through Drogheda.
There were added delays at border crossings where foot-and-mouth disinfectant controls were in place. Congestion was said to be particularly bad in Lifford, Co Donegal.
AA Roadwatch presenter Ms Morag Maxwell said motorists should expect similar delays on the roads from Monday lunchtime onwards. "They should give themselves plenty of time and plan their journeys ahead."
She also echoed calls from gardai for drivers to respect speed limits over the bank holiday period, which is often a bad weekend for accidents.
The number of people killed on the roads this year is down slightly on the same period in 2000 with 109 fatalities to date.
