How do I open the cave in Pokemon Emerald?

You need to have a Wailord in the front of your party and a Relicanth in the back. Fly to Route 134 and dive. Swim through the hole in the wall, and keep on swimming until you find some braille on the wall. Read it, then go back up to the surface. You will now be inside the Sealed Chamber. Read the braille if you like. Find a big section of braille at the back. Read it, then use Dig to open it up. Go through. Again, you can read the braille if you like, but go to the back. Make sure you have Relicanth at the back, and Wailord in the front of your party of Pokemon. Read the braille at the back, and it will shake the ground. You will hear a strange clunking sound.