20. Frozen Bubbles
Location: Most commonly located in Abraham Lake, Alberta, Canada.
These natural wonders are made of highly flammable gas methane. The gas – emitted by bacteria after they consume dead organic matter – is fairly harmless, but these bubbles can cause an explosion if lit. The strange phenomena is caused when permafrost in the area begins to thaw out. Organic matter stored in the bottom of the lake begins to thaw out, and microbes decompose it, releasing methane. Methane does not dissolve into the water, and instead forms bubbles that rise to the surface. In summer, the methane bubbles simply rise to the surface and pop to enter the atmosphere. However, when the lake is frozen in the winter, the bubbles become trapped on their way to the surface.