Air Guyane has scheduled flights to St Georges, Saül and Maripasoula from Cayenne. There's daily bus service from Cayenne to St Laurent du Maroni via Kourou, Sinnamary and Iracoubo. Taxis colectifs (minibuses), which are faster, much more comfortable and only slightly more expensive, run along the same route. Cars and motorcycles can be rented in Cayenne, Kourou and St Laurent. River transport into the interior is possible, but unless you take an expensive tour it requires patience and good timing.
Because private cars are numerous and roads are fairly good, hitching is a realistic - though never entirely safe - alternative. Competition is fierce in certain areas, such as the highway to Kourou on the outskirts of Cayenne.
In Cayenne, local buses service the beach areas of Rémire-Montjoly, but general public transport is limited, so you may need a taxi. Buses don't run on Sundays.
Cayenne-Rochambeau international airport is 16km (10mi) southwest of Cayenne. Taxis to/from the airport are available. If you're leaving French Guiana and have light luggage, a far-cheaper option is to take a taxi colectif to Matoury and walk the remaining 5km (3mi).