There are three "exploding lakes" in the world that are saturated with carbon dioxide. Underwater eruptions can cause massive amounts of this carbon dioxide to surface. A lake in Cameroon released an enormous bubble that killed 1,746 people in 1986.
Since 2008, Rwanda has been extracting the trapped methane in their exploding lake, using it to power homes. The project has been so successful that scientists and officials are looking for a large-scale expansion. Estimates indicate that, optimally, the lake's methane could provide power to 80% of Rwanda, a nation which currently has power in only 20% of homes.