How do you find the maze in pokemon sapphire for the Regis?

To find the maze for the Regis in Pokémon Sapphire, head to the Cave of Origin in the bottom right of the map, then navigate to the underwater area near Route 105. Use Surf to reach the entrance of the Ancient Tomb, where you will encounter a series of puzzles involving boulders and switches. To access the Regis, you will need to solve each puzzle in the respective ruins: Registeel's Ruins in Route 120, Regice's Ruins in the Icefall Cave, and Regigigas's Ruins in the Desert Ruins. Make sure to bring a Pokémon with Flash to illuminate the dark areas and have a few Ultra Balls ready for the encounters.