Ferry or fly between N. Ireland and Scotland

Depending where in Scotland you want to be, flying is much faster. Belfast ferries go to "Troon, Cairnryan and Stranraer" according to http://www.aferry.ie/scotland.htm although it's only Cairnryan that comes up when I try entering "Belfast" in the departure field. And indeed, these 3 locations are quite near each other, all some distance south of Glasgow.

If you want to be in Glasgow or Edinburgh and time is a factor, you're certainly better off flying.

There are budget airlines like easy jet or Ryan airlines u can ck for routing and fares. Just follow all the baggage rules very carefully. They are strict and charge alot for xtras.

If you want easy, definitely fly. Just under 30 mins from Belfast to Edinburgh. We flew Easy Jet. No probs. Just remember baggage requirements.