For most of its length it is an overgrown muddy channel, parts still holding water, parts long since infilled, and the road beside it quietly preserves the memory of an industrial ambition that collapsed within thirty years of being conceived.

Work began in 1756, designed by a man named William Ockinden, with the aim of connecting the coal fields of Duhallow to the sea at Youghal by linking into the River Blackwater. The canal was fed from the Blackwater at its western end, where a lock at Pallas once stood but has since vanished entirely. A second lock survives at Longueville, though only partially: its retaining side walls, built from coursed ashlar limestone and standing around four metres high, still frame a channel 6.62 metres wide, and a vertical niche cut into the stonework at the eastern end once held a lock gate in place. The lock itself has been shortened from its original 47 metres to just 23.5 metres; the western end was converted into an underpass for farm animals during a road-widening scheme in 1985 and 1986. Local tradition holds that the canal was laid out along the line of the Ballynoe fosse, an older boundary marking the edge of O'Callaghan's country. Near the Longueville lock, a lime kiln and a house, a lime kiln being a stone structure used to burn limestone for agricultural or building use, are thought to have been associated with canal operations. By 1786 the whole enterprise had been abandoned; it had failed to connect properly with either the coal fields or the navigable stretch of the Blackwater at Cappoquin, making road transport the more practical option. By 1842, when the Ordnance Survey mapped the area at six inches to the mile, it was already being called simply the Old Canal.

The lock at Longueville is the most legible surviving feature, its limestone walls intact enough to give a clear sense of the original engineering. The fragmentary remains of a small structure on the north bank at the western end of the lock add a quieter, less resolved detail to the picture. The road running beside the canal for much of its length makes the route easy to follow, though the channel itself is largely inaccessible through vegetation.