The town
Karongi is a lazy lakeside town built around a series of inlets, and the drive in from Kigali — which drops through the ridges and delivers you at the water — is one of the better roads in the country. There is very little of the bustle of Kigali here and not much of the resort energy of Rubavu either. That is the appeal.
On the water
Boat trips are the main activity. Napoleon's Hat, the round island offshore, holds a large fruit bat colony that pours off it at dusk — worth timing for. Amahoro Island has a bar and a campsite if you want to stay out on the water. Waterskiing is available for anyone who wants it, and swimming is safe and bilharzia-free, as everywhere on Kivu.
History nearby
Karongi has a small museum of regional artefacts. More significantly, the Bisesero memorial is about 30km away, on a mountain above the lake — the Hill of Resistance, where the local population held out for weeks in 1994 and where around 50,000 people were killed. The memorial church in the town itself commemorates a further several thousand. The contrast between the setting and the history is difficult and deliberate.
Where it fits
Karongi is the natural mid-point on a full Lake Kivu circuit between Rubavu in the north and Rusizi in the south, and the closest lake stop to Kigali if you only have one night.