The battle was likely to be set on a volcanic crater, with one or more lakes throughout it.
The later version of the arena featured a dry environment, with a volcanic rock texture listed in its texture segment and dead trees placed throughout. The only remains of this arena are the mountains in J4, which suggests that the Crater was very large, with its borders being outside of the main quadrant.
The earlier version of the arena (the one from the screenshot with the larger Phoenix) featured a more volcano-like appearance, with every single texture from it (Stage 8) being volcanic, as opposed to the later version only having one.
The available evidence points to the arena being located on the east side of the Forbidden Lands, at quadrant I4.
Crater was previously speculated to have originally been located at Quadrant D3, the location of Basaran in the Final version; due to the presence of matching trees in both arenas. Additionally; in the first public 'OPM Demo' map a copy of Avion's icon was used in place of Basaran, suggesting the presence of another 'bird' at Geyser.
Both ideas would later be discredited; the first when said trees were found to had materials that included "I4" in their name, which could indicate a potential location prior to being moved, and the duplicate Avion icon explained by users Nomad Colossus and Wisi as a leftover from an older order in which the Colossi were fought.
The J4 mountains appear to be a partial remnant of the arena, sharing many of the same unique textures listed only in Crater.
- A part of the Crater still exists outside the boundaries of the game, at J4. The materials from J4's ground remnant are named as "i4_seam_ground" and "i4_seam_ground_durt", indicating that it connected to I4 and was not moved.
- The trees that were present in the Crater are still in the final game, at Basaran's arena.
- The unused theme "Voice of the Earth" is likely to have been the intro song for reaching the Crater. The proof of this is the song's name in the debug menu of the game, which is titled "volcano".
- The theory that Phoenix lived at I4 was originally from SpaceOmega5000 (formerly known as WWWArea). Later evidence from the data sheets helped solidify it.
- Crater's chip data is full, indicating that the whole quadrant it resided on was modelled. This correlates to part of the arena expanding over to J4 and Ueda's comment stating that they needed to create a really large environment for Phoenix.
|Characters||Wander · Mono · Agro · Dormin · Lord Emon · Guards · Shadow Creatures|
|Colossi||I · II · III · IV · V · VI · VII · VIII · IX · X · XI · XII · XIII · XIV · XV · XVI|
|Locations||The Forbidden Lands · Shrine of Worship · Colossus Arenas|
|Main Items||Power-ups (Lizards · Fruit) · Weapons (Ancient Sword · Sword of the Sun · Queen’s Sword · Sword of Dormin · Bow & Arrow · Ancient Bow · Harpoon of Thunder · Life Sword) · Collectibles (Relics)|
|Gameplay||Hard Mode · Save shrines · Time Attack · Reminiscence Mode · Watermellon · Barrel|
|Media||Roar of the Earth (OST) · Official Art and Guide Book · Nico Bonus DVD · Film|
|Releases||OPM Demo · PS2 original · PS3 remaster · PS4 remake · Credits|
|Early Builds||Preview version · PSU Preview version · E3 Demo|
|Unused Content||Unused Colossi · Datamined Colossi · Colossus Test Stages · Unused Locations · Beta Mountains · Shadow of the Colossus Development Phases|
- http://nomads-sotc-blog.blogspot.com/2012/04/opm-demo.html | OPM Demo Blogpost by Nomad Colossus.
- http://spaceomega5000.blogspot.com/2018/03/theory-phoenix-was-at-i4.html | Phoenix at I4 Theory Blogpost by SpaceOmega5000.