It's been off-limits for many years to everyone except film crews, but since spring 2017 Charlestown's historic port has reopened to the public. You can now wander round the Georgian quays, and with a bit of luck, step on board a tall ship docked alongside the harbour, the Kasjamoor, built in 1939. It's worth ringing ahead to doublecheck the port is open, as it's sometimes closed for filming.
Joint tickets with the Charlestown Shipwreck & Heritage Centre are available.