The B8003 is a short piece of classified road on the Isle of Seil. It was originally unclassified but had gained its number by 1932.
The road runs from the B844 at Balvicar southwards to Cuan ferry, from where a small car ferry sails to the Island of Luing. There is a long-running debate as to whether the people of Luing would be better served by a bridge across the narrow channel than the ferry, so the B8003 may grow in length in the future.
The road itself starts at a crossroads where the B844 turns right (and keeps priority) and an unclassified road turns left. Continuing south, our road runs through fields at first, and past a graveyard before passing a small group of houses. Beyond the parish church of Kilbrandon, the fields give way to moorland, with the road then dropping quite sharply into the tiny village of Cuan at the southern end of Seil. As is often the case in such places, cars litter the verges, owned by both daytrippers and locals, before the slipway is reached, with the road very briefly widening to accommodate the ferry queue!
The 1976 OS Landranger sheet also suggests that there was a short detached section of the B8003 which follows the southern section of the former A816 route at Kilninver. This road is now a spur of the B844, and it seems most likely that this is a mapping error, as it would have involved a very long multiplex.