There is the option to see the lowland gorillas near Bukavu in Congo. Security is OK although there can be trouble at times so you need to check before crossing from Rwanda. The lowland gorillas are slighlty smaller (although they look just as big when you are sitting a few metres away) and have shorter hair. The gorillas are well habituated and you can get some excellent photos.
To get to the Kahuzi Biega National Park you can get a small motorbike (boda boda) from Bukavu town for a cost of around $4 US dollars and it takes about 30 to 45 minutes to get there from town depending on whether it has rained as the road gets very slippery. It is only a few kilometres from town to the park.
The cost at present is $300 US although there is talk of increasing the price.
Bakuva town is situated on the southern end of Lake Kivu on the DRC congo side. Cyangugu is the town on the Rwanda side of the border and it is easy to get to via Kigali, Butare where there is a great museum on Rwandan artifacts, past Nwenge Forest and down the escarpment to Cyangugu.
In addition to trekking the lowland gorillas the park HQ has a room containing bones of elephants, gorillas and other wildlife slaughtered by the Interhamwe during their occupation of the park 1997-98.
It is estimated that there are only about 30 elephants left in the area around park HQ whereas before the occupation there were many hundreds. It is unknown how many lowland gorillas are remaining in the park.