Why does Lake Kivu contain large quantities of methane?

Lake Kivu contains vast quantities of dissolved methane in its deep waters. While the lake is noted for being rich in volcanic substances, the presence of these gases is linked to the lake's unique geological environment.21

In deep, deoxygenated environments—such as the bottom waters of Lake Kivu, where 99 percent of the volume is considered a biological desert—methane becomes chemically stable. The accumulation of such gases is a characteristic shared by other deep, stratified lakes in the region, which also contain lethal amounts of hydrogen sulfide. These gases remain trapped in the deep layers of the lake due to its specific physical and chemical conditions.13