This article is written from the Real Life point of view Globe.svg

"Chozo script translated."

This article's name is an unofficial translation from official Japanese media and may not represent the canonical English name, if one exists.
An alternate name from an official source may be required.

Sector 4 (AQA) Underwater Area (セクター4(AQA) 水中エリア?)[1] is a music theme from Metroid Fusion. It was composed by Minako Hamano and Akira Fujiwara.


As its name suggests, Sector 4 (AQA) Underwater Area plays in Sector 4 (AQA) of the Biologic Space Laboratories research station. It plays in the lower area of the sector, which simulates a natural Zebesian marine ecosystem. It continues to play in this area until the endgame, where it is replaced by either Sector 3 Restore the Cooling Installation Timer Mission or Last Instructions depending upon the player's current progress.

Sector 4 (AQA) Underwater Area is a very mysterious-sounding theme. It uses harp and a female choir, and a melody performed slowly and softly on strings. This instrumentation evokes the aquatic environment, while making this song one of the most beautiful and serene themes of the Fusion soundtrack. However, it still carries the foreboding tone present throughout the Fusion soundtrack, showing that even now Samus Aran is not yet free from danger.

Sector 4 (AQA) Underwater Area can be heard here: [1]

In a prototype build of Fusion, an alternate version of Sector 4 (AQA) Underwater Area was significantly abridged; the very beginning is largely unaltered, but instead of progressing to the melody, it simply loops a few harp arpeggios.[2] This version can be heard here: [2]


  1. ^ Metroid Prime & Fusion Original Soundtracks
  2. ^ Proto:Metroid Fusion/0911 Prototype. The Cutting Room Floor (6 August 2017). Retrieved on 30 December 2018.