Aquatic Ruin Zone

From Sonic Retro

Sonic Retro emblem.svg Sonic the Hedgehog 2 (16-bit)
Aquatic Ruin Zone
Aquatic Ruin Zone
Third level, Sonic the Hedgehog 2
Number of Acts: 2
Level theme: ancient ruins
Secondary level theme: underwater
Boss: Hammer Eggman
Maximum rings, Act 1: 176 + 70
Maximum rings, Act 2: 217 + 120
Underwater areas: Yes
Non-English names:
Chemical Plant Zone | Casino Night Zone

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 manualMedia:Sonic2 MD US manual.pdf[4]

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 NakaSonic 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.Media:Mag compare12a.jpg[5] The name was eventually reused for the first Zone in Sonic Advance.

Technical information

Offset Description
0F Aquatic Ruin Zone
$2F42 ARZ Palette
$2FA2 ARZ Underwater Palette
$D4AE ARZ layer deformation info
$3FF24 Dynamic pattern reloading for ARZ
$4077A ARZ misc sprite mappings
$42438 ARZ object debug list
$45610 ARZ primary 16x16 collision index
$45760 ARZ secondary 16x16 collision index
$48E94 ARZ act 1 level layout
$49264 ARZ act 2 level layout
$BB944 ARZ 16x16 block mappings
$BCC24 ARZ main level patterns
$C1434 ARZ 128x128 block mappings
$E6294 ARZ act 1 ring locations
$E642E ARZ act 2 ring locations


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