It's fair to say that a major attraction here is the coast itself — simply driving along it to enjoy its scenic beauty, as we did. You can travel along the Antrim Coast most of the way from Portrush to Belfast, although most would agree that the very northern part just east of Portrush is the most most scenic. Every twist of the road holds some beautiful and memorable scene — a rugged coast, a charming small town, a nice beach or a castle's ruins.
DUNLUCE CASTLE. A very picturesque castle sitting on the edge of a rocky cliff, this ruin has partially collapsed into the sea. The castle is situated only a few miles east of Portrush and is very easy to get to. Legend has it the castle's kitchen collapsed into the sea one stormy night while its Lord and Lady were enjoying dinner, the collapse taking several of the kitchen staff with it (but that story is not accepted by all).
Some efforts have been made to partially restore the castle. While it's in far from pristine condition, the views of and from the castle alone make it worth visiting. I enjoyed seeing how fragments of the basalt columns (see photo directly above) from nearby Giant's Causeway were incorporated into its construction. It only takes about an hour to explore so make time to see this, especially if you've never visited a castle's ruins before.
OLD BUSHMILLS DISTILLERY. It claims to be the world's oldest distillery. Licensed since 1608 by King James I, whiskey has been made here for over 800 years. The Bushmills' folks pride themselves in the fact that their whiskey is triple distilled (supposedly a smoother drink than twice or singly distilled, though for the life of me I can't figure out why as the flavor in whiskey is mostly imparted by the oak cask in which it's stored for years).
You can take a tour of the distillery, which lasts just under an hour, though no photos are allowed while on tour. We visited on a weekend when whiskey production was at a minimum; I suspect that a weekday tour would have shown you more of the every day life at the plant. But our guide explained the process of making whiskey very thoroughly and at the end of the tour you get an opportunity for a shot of it in the 1608 Bar. And, of course, beyond the 1608 Bar a chance to go shopping in their gift shop (with a large assortment of whiskey and related memorabilia available for your purchase).
Bushmills' whiskey comes in a variety of colors and flavors. Remember that a whiskey's flavor and color is imparted by its oak cask. As Ireland has few forests, it doesn't produce any of the barrels used by Bushmills and these have to be imported (and have all been previously used). A Spanish sherry cask will give the whiskey a very different taste and color than, say, a Jack Daniel's or Jim Beam bourbon cask from the United States.
When done with your visit of the distillery spend an hour walking around the small town of Bushmill. It's a charming place and an option to consider as a travel base for exploring this region.
CARICKERY ROPE BRIDGE: A swinging wobbly suspension bridge, 90' (about 30 m) over the sea, connecting the mainland to a tiny island. Built historically by fisherman to give them access to salmon fishing nets, the place is now a tourist trap. There's supposed to be nice views and bird watching opportunities on the island but I had my fill of walking on bouncy suspension bridges hanging over deep chasms when trekking in Nepal. I can't say I enjoyed that experience and don't cross them just for fun anymore.
The Antrim coast is extensive, with lots of hills to hike and a beautiful coast to enjoy. We found particularly intriguing our visit to the "Dark Hedges". The Dark Hedges is a unique stretch of the Bregagh Road near Armoy, (about 20 minutes from the Giant's Causeway) and is a little hard to find so you might need to ask a local as you're cruising the farm roads. Over the past 300 years or so the beech trees planted by the Stuart family in the 18th century on either side of the lane have grown massively and reached across the road creating an eerie arched criss-crossing tunnel where shadow and light plays through the branches. At the end of the lane is the Stuart family's old home, Gracehill House, now a golf club. Well worth going out of your way to see.
Rathlin Island is the only inhabited island off the coast of Northern Ireland and is accessible by ferry. It's said to be a great place to hike and bike but we didn't visit it. You can read more about it here.
I could easily see spending several days making a leisurely transit from Portrush to Cardiff if time allowed (sadly, for us it didn't). But it gives me a reason to want to go back to Northern Ireland — not that I needed one. We loved our stay here!