Rúgbrauð

thumb|Baking bread in the hot sand at Laugarvatn '''''' (, ) is an Icelandic straight rye bread. It is traditionally baked in a pot or steamed in special wooden casks by burying it in the ground near a geyser, in which case it is known as or "hot-spring-bread". Modern is usually made in a square baking pan. The bread is crustless, dark and very dense, usually rather sweet, and keeps for a long time. It is often served with butter, mutton pâté, hangikjöt (smoked lamb), or pickled herring. Dry would be ground and mixed with buttermilk to form a kind of porridge. Stale is often soaked, then made into (, "bread soup") – that is, simmered with raisins and flavorings (usually lemon) and served hot with whipped cream as a dessert.

Excessive consumption of this bread is said to cause flatulence, earning it its nickname , which roughly translates as "thunderbread" or "thunderer".