you just keep going forward.
go back to the beginig of the cave
you have to beat the elite 4
Go through the cave
Go to the Turnback Cave and go through the correct doors.
It's hard but go to psypokes.com and they may have a map
turn back cave
I beat the league on Pokemon Diamond version, and there was no cave involved, if that's what you were asking.
You cannot find the Pokemon Darkrai in Turnback Cave in the game Pokemon Diamond. Instead you can find him in Newmoon Island.
She is in wayward cave.
wayward cave
The cave is automatically unlocked. To get through the cave you need to have Rock Smash, Strength, Surf, and Rock Climb.
on Pokemon diamond you have to go to through a cave in canavale city and then go to spear pillar hope you enjoy it by!