you dont even have to go in if you dont want to
Wayward Cave on route 216
Get the natinal dex
You must have transfered the Event Regigigas to Pokemon Platinum. Only then will you be able to get the three Regis.Regirock: Found in a cave on Route 228.Regice: Found in a cave in Mt. Coronet near Route 216.Registeel: Found in a cave in Iron Island.
If you enter Mt Coronet from Route 216 (from Snowpoint City), you should run into the cave almost immediately.
Cliff Cave is near Cianwood City. Just go in the cave you see and you'll be in Cliff Cave. When you pass through Route 47, and see many Cave entrances, that will also be considered Cliff Cave.
Route 216 is near snow point you have to go thought it u can't miss it
go through digletts cave
on mars
First you need to have the movie regigigas that was distributed in the debut of the 11th movie. Then, with him in your party, you go to route 228 and you will find a small cave near the exit to route 226 named Rock Peak Ruins. Inside it are a statue and some circles on the floor. Pass through all the circles and talk with the statue and Regirock will appear. The same for the other Regis. Regice cave is in the last part of Mt. Coronet before route 216 (it's named Iceberg Ruins), and Registeel is in the final part of Iron Island cave before the exit (Iron Head Ruins). If you enter in Regirock cave without the movie Regigigas, there will be a Hard Stone. In the Regice cave you will find a NeverMeltIce and in the Registeel cave you find a Metal Coat.
the dark cave can be entered on route 45 or route 46
The underwater cave is located in route 128.
You need the Event Regigias that was given away in March 2009 at Toys-R-Us. When you trade it to Platinum, Regice will be in the cave when you enter Mt. Coronet from Route 216.