The Desert Underpass (Japanese: さばくのちかどうDesert Underground Tunnel) is a long tunnel located behind the Fossil Maniac's house on Route 114 in Hoenn. The passage is found only in Pokémon Emerald and is only open to Trainers who have defeated the Elite Four and have become the Champion. A few species of wild Pokémon can be found in the tunnel, with the area's main attractions being wild Ditto for breeding (which cannot be found anywhere else in the game), and the Fossil that was not selected in the Mirage Tower earlier in the game.
From its entrance on Route 114, the Desert Underpass extends eastward through the mountains of northern Hoenn, passing north of Fallarbor Town and Route 113 before terminating in a sand-filled cul-de-sac. In the center of the cul-de-sac is the Fossil that was not picked in the Mirage Tower.