The River Lagan runs right through central Belfast and offers a good opportunity for a longer waterfront run. The run along the water is a combination of multi-use paths and riverside ’embankment’ roads.
One can do loops of various lengths, given the numerous bridges crossing the narrow river. We’ve mapped out a full 10 km route, starting at the Titanic site on the east side. Run around the marina (Science Museum, arena), and follow Orneau/Annadale Embankment south for ~5 km, crossing Governors Bridge to the west side. Then follow Stansmill Embankment north for nearly 5 km, crossing back over the Lagan Weir Bridge.
One can make the run shorter by crossing over the bridges. Good add-on/variation options are paths in Ormeau Park (east side) and Botanical Gardens (west side).