Bubbles of Lake Abrahams
Frozen bubbles under Alberta's Lake Abraham in Canada might look like winter jewels, but you wouldn't want to be too close to one if it popped: the bubbles are actually frozen pockets of methane, a highly flammable gas.
Trapped in the lake when it freezes the bubbles are actually caused by decaying vegetation on the bed of the lake. Stacked like layers of pancakes they are snow white against the clear black frozen ice.