Lake Kivu fills the gap between Bukavu and Cyangugu (in Rwanda) and stretches some 90 km north to Goma, a glittering rift-valley lake hemmed in by green hills. The water is clear, warm, and — unlike most African lakes — almost entirely free of bilharzia, which means you can swim in it. Local kids do, off the rocky points at every opportunity.
The lakefront in Bukavu is broken up by private compounds and a few hotels, but several public points still give you direct access, and a boat hired for the afternoon can take you out to the islands and inlets. Sunset over the western shore, with the Rwandan hills going purple in the distance, is reliably spectacular.