Flow

[euthanasia]

the main aspect of the album is the metaphor of the "undertow", going agains the tide (have you seen the quotes about water?)
facing up with everything pre-stablished, going against everything They Told You To Do
the complete oposite to the sheep concept, therefore the pray for self realization, and self control
"think for yourself"...

[Hyatir]

hmm could be, but i see the theme of water as being a little different. i put a post up in the prison sex catagory about this, heres some parts of it.

the theme of water in the Undertow album is introduced in Prison Sex with the words, "I'm treading water, I need to sleep a while." To me, Maynard is using water to represent his uncontrolled passions and desires which he tries to stay on top of (keep control of) and ultimately fails with later in the song. He becomes too tired to resist his desires any longer and gives in to the need.
Also, the usage of circles of behavior is shown here, as in other Tool songs. The speaker starts at the top of a circle with being taken advantage of (mentally or phyiscally, your choice) before the song takes place; he then goes on to mimic this with another person in his place, becoming the object of his fear (his abuser). Also, in disgustipated with the circles of life, and in Sober with the past actions affecting the speakers present choices so that he ends up back where he began, and in Undertow. Theres probably more, cant think of them now though.

It seems obvious, then, to compare these irreversible patterns to the undertow that sucks him down back into the ocean of uncontrolled emotion in Undertow the song. I've heard it mentioned before, and I agree, that Undertow, 4 degrees, and Flood could be thought of as 3 parts to the same song, with Undertow showing him succumbing, 4 degrees his climb out of the well of despair, and Flood showing him how the uncontrolled passion and emotions that he feared and fell prey to for so long could be beneficial if properly understood used. Just like water, when harnessed can be a machine for industry or a destructive force of nature, so is emotion. It could also be an allusion to lachrymology (this has been mentioned before for sure, but just wanted to include it), the concept of growth through pain (symbolized by crying) can be used to interpret these songs.