An ancient labyrinth situated on the seafloor of Undella Bay.
The Abyssal Ruins is quite unlike anything else in the game. To get here, you must use HM06 Dive while on top of a dark patch of water in Undella Bay. Once you’ve submerged, hold Up to keep diving, until you reach the actual entrance of the ruins.
Depending on where you dived from, you’ll begin in a different part of the first floor. So if you dived near the west of the bay, you’ll begin from the western entrance and so forth. The first thing to note: there are no Pokemon in the ruins, only rare "Relic" and "Plate" items.
The former can be sold to the item maniac in Undella Town for $$$, while the latter can be attached to the mythical Pokemon Arceus to change its type. Essentially, all you’re doing here is treasure-hunting.
As a side note, if you inspect some of the wall columns, you’ll be greeted by lines of unreadable hieroglyphs. Although if you’re a master at ciphers, it is possible to decipher the glyphs, but it’s not really important for navigating the ruins.
Secondly, you are only allowed to move 500 tiles (look on the floor and you’ll see what we mean) before you are forcefully taken outside the ruins. This is not enough time to explore the entire ruins in one go, so if you want to get everything, multiple runs are required.
1st floor: Reach the central purple column within 190 steps.
2nd floor: Use Flash next to the purple column.
3rd floor: Use Strength next to the purple column.
For your information: to reach the first purple column within 190 steps will require zero detours. Flash is gotten in Castelia City, while Strength is found in in Nimbasa City. See the relevant sections earlier in the guide if you’re unsure where they’re found.
At the very end, on the 4th floor, you can obtain the Relic Crown , which you can sell for an amazing 300,000 Poke Dollars if you show it to the item maniac in Undella Town.
So between the 190 steps needed to advance from the 1st floor and 500 steps total before you’re booted, it would make great sense to plan ahead. For your benefit, we’ve provided a set of high quality maps, below, which show all the paths and items on each floor.
Reminder : To get past the purple column, you must inspect it having walked no more than 190 steps.
Reminder : To get past the purple column, you must use Flash next to it.
Reminder : To get past the purple column, you must use Strength next to it.
Congratulations if you made it this far! No map is needed because this floor is so small and you can’t get lost. Simply move forward and grab the Relic Crown in the centre. Then just dance around or head backwards until you’re kicked out.