From Bulbapedia, the community-driven Pokémon encyclopedia.
Submarine (Japanese: せんすいかん Submarine) is a location in Pokémon Ranger: Guardian Signs. It is the first secret base of the Pokémon Pinchers visited in the game.
When Ben/Summer was captured by the Pinchers, blindfolded and disoriented, he/she placed a tracking device in the submarine so that when rescued, the Rangers can retrace their steps to find the Pinchers' hideout. Later, returning with the player, Ben and Summer explored the submarine, rescuing several of Ukulele Pichu's friends from Dolce Island. After losing to Ben and Summer at the helm of the submarine, Blue Eyes crashed it on the seafloor in anger. She later gets in trouble for this. Ben and Summer had ten minutes (fifteen if the first attempt is a failure) to escape the submarine and rescue Blue Eyes, two Pincher grunts and some of the Dolce Island Pichu that hadn't managed to get away before along the way.
The Submarine after the crash