Pokémon Ruby and Sapphire/Route 134

This route flows into Slateport City and is important for containing the Sealed Chamber, the place where you awaken the 3 Regis (Regirock, Regice, Registeel) You have to dive to get there. You can also find a Carbos and a Star Piece here if you're playing Emerald. Route 134 contains the same pokémon as route 133.