Where to get rock smach in emerald?

In Pokémon Emerald, you can obtain the HM Rock Smash from a man in a house located in the southeastern part of the town of Mauville. After you defeat the Gym Leader Wattson, head to the house near the entrance of Route 112, where the man will give you HM06. Once you have it, you can teach Rock Smash to a compatible Pokémon to break rocks blocking your path.