Find the key at a under water cave
Go through the cave of origin.
You have to get Kyogre and then go to the ciuty it is in and got to the chamber.
you can get it before the 8th gym
sootopilis city
beat the 8th gym
Go to Sootopolis.
...... stewen in emerald isn't a elite champion. there is wallace.
sootopolis city
i go to mossdeep city
in the fortree city
somebody gives it to us after beating the 8th gym
its actually the 8th gym so you need 7 badges and then it will unlock