Icelanders once used geothermal energy back in the 18th century to make their own sea salt. And then? Production stopped just a few decades later. Saltverk revived the tradition in 2011 and—hold onto your hats—all of their salt is hand-harvested off of the Westfjords. It’s produced with 100% geothermal energy, too (yep...it’s as sustainable as it gets).