New Central Statistics Office figures show the "dramatic impact" the Covid-19 pandemic continues to have on international travel to and from Ireland.
The latest CSO figures show that a total of 85,400 overseas passengers arrived in Ireland in May and 97,000 overseas passenger departed the country.
This compares with 69,400 arrivals and 73,000 departures in April and marked increases of 23% and 32.9% respectively.
The CSO said that overseas travel in May increased nearly threefold compared to the same month last year, when there were 28,300 arrivals and 36,300 departures.
But it noted that for every overseas traveller in May this year, there were 20 in pre-pandemic May 2019, when there were 1,818,900 arrivals and 1,851,600 departures.
Of the 85,400 people arriving in Ireland last month, 85.7% arrived by air and 14.3% arrived by sea, the CSO said.
Of the 97,000 people leaving Ireland, 84.9% departed by air and 15.1% departed by sea.
Today's figures also show that continental routes contributed most to the passenger traffic in May.
Some 45,400 people arrived on continental routes and 52,900 passengers departed on continental routes.
Meanwhile, 32,400 passengers arrived on cross-channel routes and 36,000 passengers departed on cross-channel routes, the CSO said.
Just 4,900 passengers arrived on transatlantic routes and 4,500 passengers departed on these routes, the CSO added.
Apart from Great Britain - which accounted for all cross-channel routes - the most important routing countries for overseas travel in May were the Netherlands, Poland, and Spain.
Looking at the year so far, the CSO said that 379,100 overseas passengers arrived in Ireland and 408,400 overseas passengers departed from Ireland.
It said this compares to both 3.1 million arrivals and departures in the same time in 2020 and 7.4 million arrivals and departures in the same period in 2019.