The Abyssal Ruins are located in a remote region in the sea. Being only in the Unova region, it is a place located east of Undella Town. To access this mysterious place, you need Pokemon that have learned the HMs Surf and Dive. During your journey, you will receive the HM Surf from Alder before reaching Twist Mountain. Dive can easily be obtained by talking to the Lady sprite in front of the houses. She will tell you that it’s a move used for dark spots in the water and it accesses the deepest parts of the ocean. Once you’re ready, you can use Surf and look for a dark circle in the water. It is about three tiles across; when you get there, press A. After your descent, you can see a huge building in the middle of the ocean.
Proceed to enter the building, and you will find that it’s not as empty as many would think it is. The strange part about it is that it has managed to stay intact all these years. There’s something about it that makes it haunted; you’ll find it out right after you take your first step inside. It says that you will hear a click. There’s something suspicious about it: every hundred steps you take, there will be the sound again, repeating itself, but getting louder. After you take five hundred steps, there will be a huge torrent of water overwhelming your Trainer sprite and the game ends – I mean, take you back to the spot you were before. Keep in mind that there are four different entrances to the Ruins. I usually take the north entrance, since it is most convenient.
The Ruins is a complex maze divided into four floors. Once you find your way to the second floor, a pillar will move out of the way, granting you access. The same will go for the next floor, except that you will need a Pokemon with the move Flash. Strange, but this will let you proceed. Finally, on the third floor, you need Strength to move the pillar out of the way and get to the final floor. This holds the rarest item which can be sold for 300,000 Poke Dollars: the Relic Crown. Each floor has unique items increasing in rarity: the first floor has elemental plates most notable for changing Arceus’ form, the second and third, Relic collectibles for selling to the collector at the Riches’ villa.
After you’ve found a map online, you can spend as much time as you want searching to get every item in there. The collectibles are worth almost 2 million Poke Dollars, so you could really profit and spend it any way you want. The mystery of the hieroglyphics still must be solved, though. Some players have deciphered it through Caesar cipher, which is a complicated term that shifts letters either up or down one position in the alphabet. They found that the letters were moved sideways, and the trend goes from one position to two and even three in the successive floors. Eventually, I believe players will be curious or mad enough to solve the mystery of the Abyssal Ruins.