Flood is the third album by Japanese band Boris. Like the previous albums, it stays lengthy and massively slow, but in addition to sludge influences such as the Melvins and Sleep, there are undertones of psychedelic rock. Upon its initial release the album did not garner many reviews (neither positive nor negative); however, it has become a cult classic among fans and was played in its entirety every night of their 2013 US-based "Residency Tour" 
After adding psychedelic and shoegaze elements to Absolutego's noise, drone and punk aesthetic on Amplifier Worship, the band focused primarily on these new shades for Flood, adding to them a riff-based stoner rock alter ego explored a year later on Heavy Rocks. Sharing the one-long-song aesthetic used for Absolutego, the back cover lists only one track, but the CD actually has the song broken into four tracks. These indexes correspond to individual movements within the song, each recorded separately due to the time length limitations of analog tape and transferred and assembled in Pro Tools. Movement I consists of a guitar echo exploration, the descending melodies overcome faster and faster by waves of reverberating drum rolls; this ushers in movement II, first with Atsuo's slow, filtered drum beat, then joined with layers of echoing clean guitar. These primary chord changes are refined for movement III, repeated at length and eventually featuring two vocal verses; halfway through, another echoing drum roll ushers in the climax of the song/album, a heavy stoner rock section with soaring vocals, Atsuo doubling Takeshi throughout. The final riff of the album repeats with distortion through to the end of the movement, with the fourth and final movement exploring the riff with clean tones once again covered in space echo.
When played live initially, only truncated versions of movements III and IV were used, as shown on Archive I and heavy metal me; later, the band would play the full song, but with movement I replaced by a drone introduction. This arrangement is featured on Boris performing flood.