At the seaports, ferries operated as timetabled on Friday.
P&O Irish Sea services between Larne, Troon and Cairnryan had spaces available for both vehicles and passengers on all sailings.
Norfolkline's evening sailings to Liverpool (Birkenhead) from Belfast and Dublin are both fully booked.
Stena Line said it had an extra 2,000 passengers on Thursday and was expecting the same on Friday.
The continuing volcanic eruption caused cancellations across Europe amid fears the ash could cause engine failures.
Experts say the tiny particles of rock, glass and sand contained in the ash cloud from the still-erupting volcano could jam aircraft engines, as has happened in previous incidents of planes flying into plumes of volcanic ash.
So far an estimated 600,000 passengers have been affected in the UK.
Extent of Iceland volcano ash cloud
The volcanic eruption in Iceland on Wednesday night sent plumes of ash thousands of feet into the air. The cloud has spread across the UK to Europe.
The spread of the ash cloud at 20-30,000ft raised concerns for air safety, forcing at least 12 countries to restrict or halt flights in their airspace.
The eruptions from the Eyjafjallajoekull volcano continue to pump out ash clouds sporadically, which means the disruption is set to continue.
Although the cloud is too high to pose a health risk, people with breathing problems have been advised to take extra care if it falls to ground level.
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