New figures show overnight trips across the Irish border reached record levels in 2022.
The Central Statistics Office (CSO) said there were more than 1.1 million overnight trips by visitors from the Republic of Ireland to Northern Ireland last year.
This compares to 756,000 in 2019, and is a 51% rise.
A total of 2.6 million nights were spent in the North by visitors from the Republic in 2022 - a 42% increase on the 1.9 million nights the year before.
The money spent by those visitors also saw a huge increase last year to more than €267 million (stg£233m) - up 65% on the €163 million (stg£142m) spent three years earlier.
While the number of holidays taken in Northern Ireland by visitors from the Republic rose by more than 50%, the number of travellers from the Republic who holidayed at home saw less of an increase.
David Roberts, Tourism NI Interim CEO, said the figures are better than they had hoped.
"These excellent results surpass even our most optimistic forecasts for 2022," he said.
"At a time when international markets have still been recovering, the additional business from the Republic has been hugely important to the tourism and hospitality sector right across Northern Ireland.
"A notable feature is that visits by RoI residents to Northern Ireland grew at a much faster rate than visits within the Republic itself," he added.