After you finish your battle at the seventh gym, a beam of light will come out from the sea. Steven will give you the TM for surf and a scuba gear. You explore the ocean and go into a cave. You will fight aqua or magma grunts and then in the end, you battle either Maxie (omega ruby) or Archie (alpha sapphire). After the battle, they will wake Groundon (Maxie) or Kyogre (Archie). They will create havoc and the earth will look terrible and then Steven comes and tells you to meet him at the Cave of Origin. Once you get there, Maxie or Archie will give you the suit you saw at their HQ. Just then, your rival comes and gets all confused and stuff. You then explore the cave and see Kyogre or Groundon in position for giving you a ride. Just then, Maxie or Archie will call and tell you to hitch a ride. Kyogre or Groundon will take you to a place with lots of crystals deep down in the earth and then mega evolve. You will have to battle them and catch them. Once you come out Maxie or Archie will apologise and if you do catch Kyogre or Groundon, Maxie or Archie will give you the orb. Steven will also give you the Eon Flute.