Brazzaville and Pointe-Noire both enjoy international connections to other African countries as well as to Europe.
Airports & Airlines
In addition to Air France, which offers international and African connections, other international airlines serving Congo include:
EC Air is the country's national carrier, based in Brazzaville, though it suspended operations in late 2016 due to debt and it was not clear at the time of writing if it will be resuming services.
You must pay CFA1000 at the airport for domestic flights within Congo if you have a paper ticket. For electronic tickets and all international flights, the tax is paid when you buy the ticket.
Crossing to Cabinda is possible on good roads, but check the situation carefully before trying it, especially if you are driving your own vehicle. This route has been subject to attacks by militia groups in the past.
Travel to Cameroon is slow-going, but possible in the dry season. The best way is to take a boat across the border from Ouesso to Sokamba, then continue through remote southeast Cameroon to Moloundou and Yokadouma. If you're driving, first head southeast of Ouesso to Ngombe, where there's a car ferry over the Sangha River, and then drive to Ngatongo, where another ferry will take you across the border to Sokamba.
Congo–Central African Republic
Between June and December, when river levels are high enough, barges run up the Congo and Oubangui River from Brazzaville. The boats used are creaky old multilevel boats that are virtual floating markets. There are hundreds of people packed on board and there's zero privacy or comfort but there is bucketloads of genuine adventure.
Some boats go to Bangui (Central African Republic) and Impfondo, and others veer left at Mossaka taking the even wilder Sangha River to Ouesso. There are more or less weekly departures (Bangui/Impfondo CFA30,000/15,000), but no schedule; boats go when they're full. Ideally the journey between Brazza and Impfondo can be done in five days downstream and nine upstream. Between Bangui and Brazza allow 10 days downstream and two weeks upstream.
To find a boat start your search at the river port in Brazza or Bangui. Take plenty of food and fresh water (although fish and fruit can be bought en route).
Although it's possible to cross the border at Doussala or Mbinda north of Dolisie (both in Congo), most people heading to Gabon travel between Oyo (Congo) and Franceville via Léconi (Gabon; it's not on the border, but take care of Gabonese immigration formalities here). There's no public transport along most of this route and few lorries, so it can take several days.
There are no scheduled services that allow you to arrive in Congo by sea.