2. Cumbre Vieja, Spain
Located in the Canary Islands, Cumbre Vieja is a volcano everyone hopes will stay dormant. Besides risking the lives of Canary Island residents, an eruption of Cumbre Vieja could potentially cause an enormous tsunami, endangering the lives of millions. While no one fears an eruption of Cumbre Vieja tomorrow, it is the most active volcano on the Canary Islands and it’s worth watching.