Undertow is the debut full-length studio album by American rock band Tool, released in 1993. Arguably their finest album, this follow-up to the 'Opiate' EP showcases Tool at their best, assisted by clean, crisp production, without the muddiness of 'Aenima.' Edgy guitar riffs are complemented by spitting, heavy bass, especially on "Sober" and "Crawl Away."
Lyrically, Tool are at their vitriolic best, targeting religious hypocrisy ("Intolerance" and "Sober"), the loss of innocence and its consequences ("Prison Sex"), and deliberate ignorance ("Swamp Song"). Henry Rollins makes a guest appearance on "Bottom," which, along with "4 Degrees," deals with questions of identity.
'Undertow' is also Tool's most musically adventurous album, lacking the occasionally numbing sameness of 'Aenima,' and with considerably more sophistication than their previous work.
"Just as grunge was reaching its boiling point and radio-friendly punk-pop loomed on the horizon, Tool released Undertow, which firmly reinforced metal's prominence as a musical style -- but, for once, it had something worthwhile to say. At the forefront of Tool's commercial explosion were striking, haunting visuals that complemented the album's nihilistic yet wistful mood. Drawing equal inspiration from Black Sabbath, alternative theories of science, and Eastern religions, Tool's abrasive sonic assault begins from the opening notes and continues through the final moments of the last composition, an open mockery of organized religion and its incapacity for original thought. With its technical brilliance, musical complexities, and aggressive overtones, Undertow not only paved the way for several bands to break through to the mainstream adolescent mall-rage demographic, it also proved that metal could be simultaneously intelligent, emotional, and brutal." (Rob Theakston, AMG)