Subterranean Gate is an Adventure Map location, that enables heroes to move between the surface and the underground layers. At the beginning of the map the gates will be paired, and they will lead to the other layer's gate nearest to the corresponding point. If two gates are at equal distance from the corresponding point, the northmost gate will be paired, and if they are at the same "latitude", the westmost gate will be paired. If one of the layers has more gates than the other, the extra (unpaired) gates will be blocked (with a pile of rubble).
Unlike most other structures, Subterranean Gates cannot be located on Water.