Di sma undar jordi, or simply di sma, are legendary vættir-like creatures found in folklore from the island of Gotland, Sweden. The name can roughly be translated as "the small ones underground". Di sma are said to take care of farms and the people and animals that live there, as long as one does not anger them. The most classical example of doing so is to mindlessly scald them when disposing hot water outdoors. According to Gotlandic tales, di sma can only be seen by looking through a hole in a sheet of paper.[1][2][3]
The Swedish rauk'n'roll[4] band Di sma undar jårdi, active in the 1980s, was named after these creatures.[5]