The cave of Registeel is in the bottom of the desert on Route 111 above Mauville City.
Kyogre.
wala
Go to Seafloor Cavern and look around.
the undersea one on route 128 i think.
u find it at the seafloor cavern
erwater cavern surrounding sootopolis city
you must have a relicanth in your party 1st spot and a wailord last spot and a Pokemon who knows dive and surf then go to paciflog town and go west and dive when you see dark water spots and look for an entrance to an underground cavern
The same way you got in, or use the escape rope or the move dig.
The main reason to be in the secret cavern is to fight with the leader of team aqua and suddenly KYOURGA will get away and fight with GROUNDON at sootopolis city.
Seafloor Cavern. To get there you need surf and dive, and once in there you will need strength and rock smash. Seafloor Cavern can be found underwater in route 128.
to catch the Regis, you first have to complete the underwater cavern somewhere around sootopolis. it REALLY helps if you can interpret braille. after that, to get to registeel's cave, which is south of fortree, on a side path, then follow the braille instructions in that cave. then a passage should open to registeel.
It's the Seafloor Cavern... An underwater cave where the legendary pokemon, Kyogre is sleeping.