The simmering, geothermal heat that powers Iceland’s geysers, hot springs and steam vents¹ also provides a natural oven for this slow-baked Icelandic rye bread.

Made with dark rye flour, the dough² is enclosed in a metal pot before it’s buried in the warm ground near geothermal springs and other hotspots. When baked in the traditional method, dökkt rúgbrauð takes a full 24 hours to cook in the subterranean³ “oven.”

It’s an ingenious use of an explosive natural resource, and in the hot-springs town of Laugarvatn, visitors can try loaves of dökkt rúgbrauð when it’s fresh from a hole in the black sand.