Exact directions- needed!!!

I can help... You need a relicanth and a wailord in your team. And a Pokemon that knows dive, one that knows surf, and a Pokemon that knows dig because you use that in the cave that unlocks the regis. You will also need a braille guide, to decipher some writing that is in braille. I will tell you a step by step guide on how to get there. I might cut and paste it into the hints section for this game, too, just so anyone can find it, because it has been asked before, a fair bit. Also, you won't find the regis there, you will be able to unlock them from there, though. I will also tell you the general area that the caves that the three regis are located. (yes they are the rocks with the six smaller rocks around them that people mentioned. The dive square only has four rocks, and currents all around.

Anyway. Have relicanth in your party. Have wailord in your party (you need them to unlock the regis.) have a Pokemon that knows surf, dive and dig. (any just so long as you can use those moves)

FOR EMERALD (it's the same for ruby/sapphire, except some of the people I describe, may not be there in the earlier games. But the landsccape is the same.)

Fly or go to Pacifidlog town. In the ocean in southern Hoenn.

Surf west/left to the strong currents that carry you away, but DONT GO IN THEM YET. Go near them and look at them, go south a bit, and you will find that the line of where the current starts is a bit jagged, the currents start in different spots. You need to find the one that pokes out.
I_
___I
I___ <- go here.
I_
I_
Strong currents __I XXXXX
_I XXXXX <-Rocks
__I xx XXXXX
I__ xx

---hope the map worked---
If you surf down low there, near a big rock and some smaller rocks, you will be buffeted by the currents onto an island right into a fisher man. Battle him. Then walk to the west/left part of that island, then you will see another sand bar island to the west. Surf to that. Don't miss it. There will be an old man and a cool trainer girl (darcy) running up and down in front of him. You may battle them if you wish. The island will have a square of calm in the middle. Go to the bottom east/right corner of the island, and walk a straight line left to the edge of the other side of the island... There will be an old woman near there with a cool trainer boy running up and down in front of her. Battle them if you wish, but go back to the exact spot you stopped. Then walk south till you stop at the edge. The bottom left corner of the island... Aim yourself to the water facing south. And surf from here. It is important you do this because you will be carried upwards in a large current.

You will be carried to a calm spot where there are two swimmers going up and down near eachother. Battle if you want, bit go west past them, avoiding the current. You will see a rocky island to the west. Surf to it.

There will be a max revive in a pokeball on the island. Get it and go to the south-western most corner of the isle, and walk up till you stop on a rock. Then walk left till you stop at the edge go up one step, then west/left till you stop at the edge. Surf from here. It's important to surf from this spot, and not to move at all when you get to the next sandbar...

The current will carry you to a sandbar that is kind of rectangular-ish.DO NOT MOVE YET. In the exact spot where you landed on the sand-bar just walk directly in a straight line west (in front of you) and surf again from here. (if you aren't in the right spot exactly, don't worry, when you surf left/west, you will see the dive spot, but currents around it will carry you away. Just go to the sandbar as per my instructions and try again)

And look where you are! If you followed it ok you should be there! Dive here, and swim south, and you will see some braille on the wall. Read it... It says "go up here" face the braille and dive up in that exact spot (anywhere else and you'll return to the surface) and you'll be in the cave. In the first room there are rows of rocks with braille on them, the long ones reading from left to right, top to bottom have the braille alphabet. The two small ones have comma and period on them. At the other end there is braille on the wall. It says: "dig here" so dig in front of the door. Instead of going to the start of the cave, a door will open up. Go in.

There will be six rocks in this room that look like the rocks around the three caves the regi's are in. There is braille in this room. Giving you back story on the regis and ancient hoenn. Read it. On the far wall, there will be more braille. I think it says "first comes relicanth, last comes wailord" so put them in those spots in your party and look at the braille again. You will hear some stuff and that means the regi caves are open! (if it doesn't work, then try putting relicanth last, and wailord first.

The three regi caves are in other parts of hoenn. The regis are one chance battles so don't knock them out. They are at lv40 I think. In each cave, there is only two rooms. There is a fore-chamber, in which there is more braille to open the door to the room in which the regi is. It involves either going to the center of the room and using fly, walking left and using strength (i think) and waiting for a minute without moving... It is this last one which stumped me. I can't remember which caves they are in.

Regirock:Desert Ruins: It's cave is in the desert, in the south part of it, near the ruin maniac. You may have seen it, but now there is a door.

Regice:Island Cave: it's on a little sand island on route 105, if you surf north of rustboro city. Surf about and you will find another ruin maniac.

Registeel:Ancient Tomb: it's on route 120, near a little girl who gives you berries. Head west of Lilycove, and just as you get to the part where you have to start going north into the rainy parts. As you get to that corner, there is a pond and a staircase, go up and another ruin maniac will be there. And there's your cave.

I found registeel the hardest to catch, and regirock the easiest... But it might just be me.

Hope I helped!

N.B.: if the map didn't work, then just surf from the south area of the beginning of the strong currents!)