Ferry passenger numbers are down over 17% at Dublin Port in the first three months of the year, compared to 2019's figures.
Figures show the number of tourists passing through has also fallen by 18%.
Meanwhile, overall the number of goods passing through in the first quarter is down almost 5%.
The new figures come as the country remains in lockdown following the Taoiseach's announcement that restrictions on movement will remain in place until next month.
Leo Varadkar speaking on Friday extending the restrictions, acknowledged that there was anecdotal evidence of people coming into Ireland by boat ahead of the Easter weekend - but said that the majority of these were Irish citizens "returning home" and not tourists from overseas.
Labour leader Alan Kelly claimed that there were "dozens of cars with UK registrations" coming into the country on Good Friday.