By train
Saint-Malo's train station is located over a kilometer south of the intramuros area, but it's an easy 20-min walk straight down Avenue Louis Martin. There are a few direct TGV services daily from Paris Gare de Montparnasse, which take about three hours. Most travellers, however, will end up connecting in Rennes, from where there are hourly commuter services 50 min, €12 to Saint-Malo.
By ship
From the UK you can arrive from Poole and Weymouth on Condor Ferries. Leaving from Portsmouth with Brittany Ferries. From Jersey & Guernsey you can take Condor Ferries which offers direct routes from both islands.
By bus
There are two buses daily to Pontorson line 17, 1 hour, €2,5, which depart from the train station and stop at the city walls. The buses are timed to connect to onward buses to Mont Saint Michel 15 min, €2, allowing a fairly comfortable day-trip.