How do you catch regi rock regi ice and regi steel on Pokemon sapphire?

first you need a relicanth and a wailord. Go to Pacifidlog town, form there ride south on the ocean currents. When you get to a square dark patch dive down. Look at the braille then resurface, after that, use dig. Put relicanth first and wailord last. then click on the farthest door, the regies appear and you can catch them.