Aquatic Ruin Zone is the third Zone in Sonic the Hedgehog 2, and is the token underwater level of the game. Pieces of Roman ruins are dotted around this vast lake, and some of them have tendencies to rise out of the ground in front of the player, break off the ceiling above them or sink into the water. There are also arrow launchers built into the pillars that will shoot arrows at the player should they pass them.
In the Simon Wai prototype, this was actually the first level.
||Roaming Romans infest a beautiful forest and sunken lake. Explore an intricate maze. If you're underwater, breathe the air bubbles to keep from drowning. A countdown begins when your oxygen's running out.
— Sonic the Hedgehog 2 US manual
||The top and bottom of this stage are built completely differently. The loops along the top are a bit different from normal. The water, also, had to have the transparency set exactly right. And then, there are so many places where the routes intersect! From Sonic 2 on, we took a patent in America.
— Yuji Naka, Sonic Jam Official Guide
- Grounder - Drill enemy, hides behind walls and appears when Sonic approaches.
- Whisp - Fly enemy, attacks in swarms.
- Chop Chop - Piranha enemy, moves around slowly underwater.
Aquatic Ruin, up to some point in development, was named Neo Green Hill Zone which can be seen in the Level Select of the Simon Wai prototype and in an early screenshot of the game showing the title card “Neo Green Hill Zone”, although the "HILL" was glitched and displayed bubble sprites. The name was eventually reused for the first Zone in Sonic Advance.
|| Aquatic Ruin Zone
|| ARZ Palette
|| ARZ Underwater Palette
|| ARZ layer deformation info
|| Dynamic pattern reloading for ARZ
|| ARZ misc sprite mappings
|| ARZ object debug list
|| ARZ primary 16x16 collision index
|| ARZ secondary 16x16 collision index
|| ARZ act 1 level layout
|| ARZ act 2 level layout
|| ARZ 16x16 block mappings
|| ARZ main level patterns
|| ARZ 128x128 block mappings
|| ARZ act 1 ring locations
|| ARZ act 2 ring locations