The tunnel on top the ruins is accessible.
The tunnel is where you catch the ? and ! Unown.
Chat with our AI personalities
If you catch 26 Unown in Pokemon Diamond, go to Ruin Maniac Cave. He will be waiting inside for you. You can catch Hippopatos in the cave, along with Geodude. Go to the end of the cave where there is another entrance. Go through, and when you get inside, you will see a writing on the wall. It says, "?!" Those two Unown are in there. Capture them. You now have all the Unown.
Each letter of Unown has its own room, which means that you cant catch all types of Unown in the same room. But you can catch multiple copies of the same Unown in its room.
Unown (often wrongly spelled as Unknown) is a Pokemon in the Pokemon series. If you catch one of every type, a new part of their cave will be opened.
In Diamond/Pearl/Platinum, after you have caught all the Unown the Maniac Tunnel on Route 214 will be fully accessible, now you can catch the "?" and "!" Unown.
Nothing happens, except the fact that you have many Unowns. ~Katie