The Plym Valley Railway is a volunteer-run heritage line on the northeastern edge of Plymouth. Its short rides, restored rolling stock, and station atmosphere make it a gentle railway outing rather than a major transport museum. For families and rail enthusiasts, that can be exactly enough.
The railway works best when services are running, so check operating days before travelling out. It can be combined with walking or cycling in the Plym Valley, giving the visit a bit more substance than the train ride alone. Treat it as a pleasant half-day extra after Plymouth's waterfront, Barbican, and maritime sights.