Jamestown Quay is a pleasant mooring spot. There are not too many boats since the bridge marks the end of the navigable part of the Shannon.
The Shannon loop between Jamestown and Drumsna has lots of shallows. It can only be explored by Dinghy. Cruiser traffic has to go through the Jamestown Canal.
Between Jamestown and Drumsna the Shannon forms a loop towards the north. It marks the boundary between Co. Leitrim and Co. Roscommon. When you come from Jamestown (Co. Leitrim) and cross the bridge, you find yourself in Co. Roscommon.
After about 1km, you go over the Drumsna Bridge which brings you into Co. Leitrim again. The N4 used to run over Jamestown Bridge and through the town until the by-pass was built in 1996.