Short answer: The quay and the waterfront streets are level and the ferries make good accessible transport. Blackpool Sands has a boardwalk down to the water. Dartmouth Castle has a lot of steps and is not suitable for pushchairs or wheelchairs.
Dartmouth is built on a hillside above the river, and the streets climbing away from the water get steep fast. The waterfront itself — the quay, the Embankment and the streets immediately behind — is level, and that is where almost all the good eating and the boat departures are.
The ferries here are real transport rather than a novelty, and for anyone with wheels they are the easiest way to move around. Boats run downriver to the castle, across to Kingswear for the steam railway and upriver towards Totnes. Board on the flat, arrive on the flat, and skip the lanes entirely.
Fifteen minutes west and the standout for accessibility on this stretch — reviewers specifically praise the boardwalk running from the beach area down towards the water, which is a rare thing on a Devon beach. There is a car park you pay for on exit, toilets, showers and a café. It is fine shingle rather than sand, so beach shoes help. The approach road is steep and narrow.
Worth saying plainly. Dartmouth Castle has a lot of steps and reviewers are clear it is not good for pushchairs or wheelchair users. You can still take the ferry out, enjoy the approach and the tea room, and treat the fort itself as something to look at rather than climb.
The Sail Loft on Foss Street is the roomiest place in town, with a big characterful room and space to manoeuvre. The Royal Castle on the quay has high chairs and level access from the waterfront. Café Alf Resco has a covered courtyard and is dog friendly, though it is small and queues.
Two to know about: Bespoke does the best coffee in Dartmouth but is explicitly too small for pushchairs or walking frames, and the Dartmouth Arms has steep stairs up to the toilets.
See the full Dartmouth guide, filtered by who's with you.
Plan your day near Dartmouth →