Thousands of people passed through Northern Ireland's airports, as people travelled ahead of Christmas Day.
Belfast International Airport was expecting 20,000 passengers a day in the run-up to Christmas.
George Best Belfast City Airport expected about 10,000 passengers a day to pass through its building.
Its Operations Director, Mark Beattie, said that its flights "are operating to capacity".
"There will be northwards of 120 [flights] each day at the airport, so quite a lot," he added.
"On Christmas Day the airport is closed, the only day it is fully closed.
"From 04:30 on Boxing Day, all the staff will be back here for first departure at 06:40."
Mr Beattie said Belfast City Airport provided musical entertainment for passengers on Monday, including a choir and a pianist.
He said that passengers should not bring wrapped presents in their hand baggage.
"We have a complimentary service near security where passengers can get their presents wrapped," he added.
Mr Beattie said that he hoped the Christmas period would go smoothly and there would not be travel disruption due to inclement weather.
"We have our normal plans in place, we get a detailed forecast from the Met Office and over the next five days it is reasonably favourable, hopefully everything is fine."
Belfast International Airport said it had also provided musical entertainment for passengers over the Christmas period, including various choirs, with "lots of meeters and greeters in arrivals".
It said there would be no flights on Christmas Day, but the airport would "remain operational in the event of an emergency or diversions".
"Boxing Day is when you have the festive getaways, with people going skiing and passengers returning back home again," a Belfast International Airport spokesperson said.
City of Derry Airport said about 5,000 passengers would have passed through its terminal between Wednesday, 18 December, and Christmas Eve.
It said it would close on Christmas Day and reopen on Boxing Day.
Thousands of people are also expected to make the journey by sea with Stena Line saying 36,000 passengers will travel through the port at Belfast.
Elsewhere, Translink says holiday timetables are in place over the Christmas period and it is urging passengers "to plan their journeys in advance".
There is no service for Ulsterbus/Goldline, the Metro/Glider or NI Railways on Christmas Day.
More information is available here on the Translink holiday timetables.