Bujumbura International Airport is located about 12km north of the city centre. Thanks to the protracted war, very few international airlines still serve Burundi, and Air Burundi itself, the national airline, has suspended operations and now functions only as a travel agency.
Kenya Airways Hub: Nairobi.
RwandAir Hub: Kigali.
Burundi shares land borders with the DRC, Rwanda and Tanzania.
The main crossing between Burundi and the DRC is at Gatumba on the road between Bujumbura and Uvira (the DRC), about 15km west of the capital. There's very little onward transport to Bukavu (the DRC). It would be wiser to stay on the Burundi side of the border and travel to Cyangugu in Rwanda and cross to Bukavu from there. Whichever way you do it, be sure to check the security situation in DRC first.
The main crossing point is between Kayanza (Burundi) and Huye (also known as Butare, in Rwanda) on the main road linking Bujumbura and Kigali. The quickest option for travel between Bujumbura and Kigali is to use one of the scheduled bus services listed following (six hours, BFr13,000), which pass through Huye (four hours, BFr13,000). Buses depart hourly from 6am to 1pm from the Siyoni bus station, although some have booking offices in the centre of town.
Horizon Coaches Has frequent services to Kigali.
Yahoo Car Express A couple of buses a day to Rwanda (Kigali and Huye).
Volcano Express The best, and most frequent, service to Rwanda. It has a booking office in town but buses depart from the Siyoni bus station.
For Kobero, the trip is done in stages via Ngara (Tanzania). There are daily buses between Mwanza (Tanzania) and Ngara, from where there is onward transport to the border. From Kigoma (Tanzania), take a bus to Nyakanazi (Tanzania) and get onward transport to Ngara from there.
For the Manyovu crossing, there is a daily bus operated by Hamza Transport between Kigoma and Bujumbura at 7am. The journey takes eight hours and costs Tsh8000. Cargo boats sail around three times a week between Kigoma dn Bujumbura and it might be possible to negotiate a lift. The trip takes around 18 hours.