By ferry is by far the most common approach. CTM Deher and L'Express des Îles both operate from the ferry terminal in Pointe-à-Pitre (Gare Maritime de Bergevin) to Grand-Bourg on Marie-Galante. The crossing takes around 45 minutes on the fast ferry. Several departures daily, more on weekends. Tickets cost around €25–30 each way; book online in advance during holidays.
There is also a less frequent ferry connection from Saint-François on Grande-Terre, useful if you are staying in that part of Guadeloupe.
By air, Marie-Galante Airport (IATA: GBJ) receives small aircraft from Pointe-à-Pitre's Pôle Caraïbes Airport. Air Antilles and Guadeloupe Air Services offer inter-island flights; the flight takes around 20 minutes. Useful in rough weather when the ferry is uncomfortable, but not significantly faster door-to-door.