The B146 is a loop off the A2 serving the Giant's Causeway. It is part of the Causeway Coastal Route. The road was originally unclassified but gained its number in the late 1920s.
The road turns off the A2 opposite the Smugglers Inn and heads north along Causeway Road, with the sea becoming visible almost immediately. The road bears right at a minor road providing access to the Giant's Causeway and Bushmills Railway, then right again at the main entrance to the Giant's Causeway complex. We climb past the overflow car park and continue east, with the sea out of sight behind the ridge on the left.
Presently we start to descend and then the sea becomes visible again. A lay-by (clearly a bypassed section of B146) provides parking for Dunseverick Castle, after which we run through Dunseverick itself. Here the road turns inland and climbs to the south to end at a T-junction back on the A2.