The Pits of Hathsin are a system of caves near Luthadel on Scadrial in which Atium crystals grow. It is also a skaa labor camp the Lord Ruler set up to mine Atium crystals. It serves the dual purpose of punishing skaa criminals and concealing the location of the Atium mines, as the prisoners cannot leave.
Allomancy cannot be used to retrieve the crystals, as an Ironpull would cause them to shatter, so the imprisoned skaa have to mine it by hand. All skaa in the Pits have small scratches along their arms from the jagged crystals. The Pits are overseen by House Venture. Each skaa must find an atium geode every week; if they fail, they are beaten to death savagely.
Kelsier is the only known person to survive the pits. He was there with his wife Mare as punishment for sneaking into the Kredik Shaw. Mare dies in the Pits, and Kelsier Snapping and escapes.
Only days before the fall of the Final Empire, Kelsier returned to the Pits, destroying all the atium crystals he could find, and setting all the skaa prisoners free.
The Pits are also the location of the liquid form of Ruin, the counterpart to the Well of Ascension.[citation needed]