Pokémon Adventures, Vol. 18 by Hidenori Kusaka

On an accidental seafaring adventure in a submarine, Ruby discovers something mysterious deep beneath the waves. Then fishing nets him another Pokémon. But is his growing team bringing him closer to - or farther from - his dream? Next, Ruby must face his scariest opponent yet...his father! Meanwhile, Sapphire is having trouble getting in her quota of Gym battles. One Gym Leader wants to just hand her a badge without a proper fight! And another has been...kidnapped?