They look ethereal,these icy circles are frozen methane bubbles that when trapped underwater and frozen, form a spectacular landscape. Found in winter in high northern latitude lakes like Lake Abraham in Alberta, Canada, these gas bubbles are created when dead leaves, grass and animals fall into the water, sink and are eaten by bacteria that excrete methane.It’s a stunning, but potentially dangerous sight. This greenhouse gas not only warms the planet, but also is a highly flammable spring, when the ice melts, the methane bubbles pop and fizz in a spectacular release – but if anyone happens to light a match nearby, the masses of methane will ignite into a giant explosion.

Curious travellers can see these gassy hiccups in lakes across Canada’s Banff National Park, or in the Arctic Ocean off Siberia, where researchers have found gargantuan gas bubbles as large as 900m across!