Geologists believe Lake Bunyonyi was formed approximately 8,000 years ago, a result of a volcanic eruption in the Ruchiga mountains near the present-day village of Muko on the north-west tip of the lake that effectively dammed several river valleys with lava flows. This natural damming process of the River Kabaga created a deep basin that gradually filled with water, resulting in a lake whose depth is still debated but is often cited as the second-deepest in Africa, plunging to estimates of up to 900 feet in places. This incredible depth, combined with its location at an altitude of over 1,900 meters, contributes to its most famous characteristic: the absence of crocodiles, hippos, and bilharzia. This makes its crystal-clear waters not only safe for swimming but irresistibly inviting. The lake's current outlet is a small stream by Muko, which flows into the Ruvuma swamp. The landscape is defined by these steep, contoured hills, meticulously sculpted into agricultural terraces that climb from the shoreline like giant green staircases, a testament to human ingenuity working in harmony with the terrain.