|This article is written from the Real Life point of view|
The theme plays in the swampy entrance portion of Area 5 (where the Phase Drift is obtained), starting in a water-filled room. It features deep instruments similar to those heard in the Pirate Homeworld theme in Metroid Prime 3: Corruption, but while that theme sounded sinister and foreboding, the instrumentation of Area Indefinite gives this track an exotic jungle vibe instead. It also includes a bar from the Metroid II: Return of Samus Title theme originally composed by Ryoji Yoshitomi.
The theme can be heard here.