The island is a no car zone and you can only reach Bréhat by boat.
Les Vedettes de Bréhat is the sole ferry company transiting all year round leaving from the Pointe de l'Arcouest, north of Paimpol. The journey takes only 10 mins with departures every 30 mins in average. The ticket costs around Euro 10 in peak season.
They also offer day trips departing from the nearby seaside resorts of Erquy, Saint Quay Portieux and Binic. You can also touring for a 45 mins guided boat trip around the archipelago.
How to travel to Paimpol, Bréhat's nearest mainland travelling point:
By Road: 5 hours drive from Paris (492km) by motorway A11 and N12 from Rennes
By Sea: nearest ferry port is Saint-Malo (132km by N176 & N12 or 1h46mins drive) and Roscoff (116km by N12 or 1h40mins drive)
By Train: 4h20 from Paris to Paimpol by high speed train (TGV) with one change at Guingamp for the regional railway network service (TER)
By Plane: Dinard airport (118km, 1h34mins drive), Rennes airport (145km, 1h49 mins drive)