Irish Continental Group, which owns Irish Ferries, said tourism bookings suffered after the Brexit vote but have since recovered.
The company’s latest half-year results show revenue was up 5.2% to €150m over the six months to the end of June, when compares with the same period in 2015.
Earnings after day-to-day expenses (EBITDA) jumped 19.6% to €30.5m, while earnings per share was 32.1% higher at 10.3c.
ICG’s car volumes between January and June stood at 170,500 (+5.5%), with the number of container volumes shipped during the period up 7.4% to 152,700.
Net debt more than halved in the first half of the year, falling from €44.3m to €18.9m.
ICG Chairman John McGuckian said earnings underpinned by strong car and freight volumes, lower fuel prices and increased charter revenues.
He added: “Tourism carryings over the key summer months were broadly in line with expectation though the continuing sterling weakness since the end of June has resulted in lower euro equivalent tourism yields.
“The UK Referendum result has, to date, had very little impact on RoRo freight volumes which remain strong.
“Notwithstanding the impact of weaker Sterling ICG is well placed to benefit from the underlying growth trends in both car and freight volumes.''