Mount Nyiragongo is a stratovolcano in the Virunga Mountains associated with the Albertine Rift. It is located inside Virunga National Park, in the Democratic Republic of the Congo, about 20 km north of the town of Goma and Lake Kivu and just west of the border with Rwanda. The main crater is about two km wide and usually contains a lava lake. The crater presently has two distinct cooled lava benches within the crater walls - one at about 3175m (10,400 ft) and a lower one at about 2975 m (9800 ft). Nyiragongo's lava lake has at times been the most voluminous known lava lake in recent history. The depth of the lava lake varies considerably. A maximum elevation of the lava lake was recorded at about 3250 m (10,700 ft) prior to the January 1977 eruption - a lake depth of about 600 m (2000 ft). A recent very low elevation of the lava lake was recorded at about 2700 m (8800 ft). Nyiragongo and nearby Nyamuragira are together responsible for 40% of Africa's historical volcanic eruptions.
I wrote a technical paper about the Nyiragongo published in:
Detay M. — Le Nyiragongo : volcan de tous les dangers et maîtrise des risques, in LAVE, revue de l’association de volcanologie européenne, 153, 16-29 (2011).
You can access the paper here
Some picture have also been publised in the following books:
'Chasseurs de volcans'. Published by Omnisciences. ISBN 978-2-916097-42-8 link 'Volcans. Du feu et de l'eau'. Published by Belin Ed. ISBN 978-2-7011-7561-4 link