Suigetsu transforms into a wave of water which crashes into the opponent. He then rushes behind the opponent with the lower half of his body still being waves and slashes them in half with the Kubikiribōchō.
The Hydrification Technique's name is intended to be a pun. "Suika" (水化) is the Japanese term for "hydration", but separately, the kanji mean "water" (水) and "to become" (化) respectively, translating to something more similar to "hydrification" ("to become water"). This explains the effect of this technique more precisely.