In "Pokémon Emerald," the Terra Cave moves to one of four different routes. The Weather Institute in Hoenn tells the player which route to visit. Once informed, the player has a set amount of time to get to the location of the Terra Cave before it resets.
The Terra Cave may appear in Route 114, Route 115, Route 116 or Route 118 in Hoenn. The Weather Institute informs the player that there is strange weather in the area. The weather only starts to change once the player has defeated the Elite Four. The Marine Cave can also be found this way.