Union Cave

Union Cave (Japanese: つながりのどうくつ Linking Cave) is a cave located in the Johto region. The main cave divides from, though two other exits in the basement levels of the cave lead to the Ruins of Alph. A  can also be encountered deep in the cave every  after Morty has been defeated (as  is required to get to it).

Geography
Union Cave is a simple cave, with many pools of water. The main floor has two different ladders, both in the southern area' and on opposite ends of the cave'. The upper ladder leads to B1F, which, after crossing the pond, will lead to the Ruins of Alph. The lower ladder leads to a small hallway, which also has a pond, and the ladder to B2F. The lowest level of the cave has several ponds, the southern-most containing, on Fridays, a Lapras.

In the Pokémon Adventures manga
Union Cave appeared in Off Course with Corsola, where was traveling through the cave to get to the western part of Johto. While going through the cave, she noticed a, which was not native to the area. She was then attacked by a group of Magneton, all of which belonged to Lt. Surge, who had ordered them to catch any wild Pokémon passing by. When the Gym Leader himself arrived, he saw that his Poké Ball trap hadn't caught anything, leading him to believe that the commotion was just a false alarm. He then proceeded to exit the cave through an underwater tunnel, not noticing that his Magneton had dropped the unconscious Crystal into his submarine.

In the Pokémon Gold and Silver: The Golden Boys manga
Union Cave appeared in Extreme Power!! The Friday Pokémon where 🇬🇼 tried to capture a Lapras but failed. 🇬🇼 took in Black's Bayleef after Black left it behind.

In the Pokémon Pocket Monsters manga
Union Cave appeared in Escape from Magma!? of Pokémon Pocket Monsters. and his Pokémon went there by traveling on a Lapras. Inside, and some s took over the cave by building an amusement park. As Red and his Pokémon went in, it turned out to be a trap as Giovanni sealed the entrance. The group managed to escape when 's digger drill dug a hole. However, it took them deeper in the cave where Giovanni found them and summoned his from a lava pit.

In other languages
Einheitstunnel Cueva Unión Caves Jumelles Grotta di mezzo つながりのどうくつ 互连洞