Rob Theakston. Undertow Review // AllMusic.com, 2 юли 2001. Посетен на 22 май 2007. 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 [...] With its technical brilliance, musical complexities, and aggressive overtones, Undertow not only paved the way for several bands to break through to the mainstream [...], it also proved that metal could be simultaneously intelligent, emotional, and brutal.