The Rock Tunnel is a naturally formed underground tunnel. Since it has not been developed, it is pitch black inside. A light of some sort is needed for travelers to find their way, so it is recommended that Pokémon Trainers bring along a Pokémon that can use Flash outside of battle.Rock Tunnel is the only alternative route to Lavender Town, as the two other routes have been rendered inaccessible by a slumbering Snorlax and the Saffron City gatekeepers. The cave has two separate floors, both of which are roughly the same size. There are many Trainers within the cave, there for the fun of exploring, training, or are simply lost in the darkness.Route 10 leads from Cerulean City to Rock Tunnel. At the northern entrance of the cave is a convenient Pokémon Center. The roof of the Kanto Power Plant can also be seen from here.The southern entrance exits onto the remainder of Route 10, leading to Lavender Town.