By ship
You can arrive by boat from Brazzaville, if you have a visa. There are speed boats that go quickly for a limited number of people, or you can take the barge with local merchants if you have time. Ask to go to "the Beach", which is the ferry terminal.
By train
The railroad of Congo once covered the entire country during colonial times, but has fallen in to heavy disuse. While there is a central train station in Kinshasa, train service is erratic at best and does not run to many destinations for tourists. Tickets are usually only able to be bought the day of travel shortly before the train arrives and can prove to be difficult to get.
Kinshasas main train station is located on Place de la Gare which is at the end of Boulevard du 30 juin.
By car
Apart from the road Matadi to Kinshasa a car is no means for overland travel. You might be successful with a 4x4 in the upper northern region Bangassou - Nia Nia - Isiro and maybe the axis Kinshasa - Lumumbashi. All other towns are accessible only by air transport or boat.
By plane
South African Airways, Kenyan Airways and Ethiopian airlines and Royal air Maroc each have a number of flights per week from their hubs in Johannesburg, Nairobi, Addis Ababa and Casablanca.
Connections to Europe can be made with Air France from Paris, France , Brussels Airlines from Brussels in Belgium,Turkish Airways from Istanbul and Royal air Maroc from Casablanca in Morocco . Hewa Bora also offered flights to and from Europe until they were placed upon the EU's no-fly blacklist.
The Kinshasa airport used to have a terrible reputation for corrupt officials asking for bribes. They have improved things and it is quite manageable. Just follow everyone else and try not to look like a tourist! A yellow fever vaccination certificate is essential. Watch out for being mobbed by volunteer 'helpers' once you are outside the airport, who will want to carry your bags in return for tips.
Keep in mind that when returning to the airport to leave you can not drive your car or take a cab onto the airport property without paying for parking / access $5 or $10.
A taxi into town will probably cost you $30-$50 usually without air conditioning!. It is an hour's drive into the centre of Kinshasa. Best option is to get a shuttle offered by one of the travel companies on the right outside the arrivals door.