Sûrag is an Underdark passage that starts at Gholompotl. It heads northeast to Mulun-Dûna. It continues through the town for five miles and then splits, with one road heading to Ghaundan and the other to Nurum-Maluk. Along the Underdark passage are many caverns and adjoining passages. One of these which is blocked off with walls and towers is Atúb Mol.

The Sûrag passage was expanded to Mulun-Dûna by the Khazarkar Empire. Before the Khazarkars came to central Cinazan, the passage was narrow, often treacherous, and took three times as long to reach Mulun-Dûna. It has been greatly expanded so that two carts may pass each other. It is maintained by the Khazarkar Empire but patrolled by soldiers from Mulun-Dûna.