i dont remember if u use flash you don't need to use it any way. you just go straight if it isn in ruby/sapphire/emerald
Use fly or flash in the middle or do a lap around the cave.
U will need flash for this. once you have flash you stand in the middle of his cave and use flash then go in and catch the FUTHAMUKA
you get let all around the cave
Item needed is at least 50 ultra balls, Pokemon needed it actually doesn't matter you can have any Pokemon that knows fly or flash if your playing emerald all you need to do is run a full lap around the cave. If your playing ruby or sapphire use fly or flash in the middle of the cave.
YOU DO NOTHING
You be stupid!
It means to use flash in the middle of the cave
Regice's cave is in Mt. Coronet. Go from Oreburgh City Mt. Coronet Entrance and surf on the northern part of the water. Use Rock Climb on the rocks and go up the 'staircase'. Keep going straight until there is a bend. The cave should be between two rocks. Regice will not be found in there unless you have the movie Regigigas with you.
You have to Run around the Cave 3 times
the cave of regis is a place where you unlock 3 regi doors registeel, regice regiggis the other is in the sapharie zone
use the hm flash. the cave isnt too hard.
They are on route 79,56, and 54. But you need some sort of item to get into the cave of regice.