Not got rigis yet.

First you must have a Wailord and a Relicanth. Then you must go the Sealed Chamber. It is in the Ocean Current on Rout 134.

Well, it kinda of a long process that you need to go through in order to get to the three Regi's. Firstly, you need to get all the way up to Pacifilong town. Once you get there, you can worry about getting to the three Regi pokemon. Second, you need to catch the two Pokemon Relicanth, and Wailord. You can get a Wailord by evolving a Wailmer at level 40, or by catching one on route 129. As for Relicanth, well, all you need to do is look for him in any area that has underwater grass.

Now surf west of Pacifilog town, and head into the current. You need to kind of get in the middle before you surf the currents because you are trying to reach a small area that will take you underwater. If you cannot get it in a few tries, look on youtube for the correct path. I used a video tutorial on how to get there for my first try as well. After that, just use dive again when you are at the cave, and go in. Proceed through the cave, and click on the giant wall of braille at the end, you should hear and see a rumble, or earthquake of sorts.

That signifies that the dorrs to the caves' are now open, and you can go in, and catch the three Regi pokemon.

Hope this helps.