Synonyms for Subaquatic (same or very similar meaning)
WordNet sense 1 (growing or remaining under water):
subaqueous, submerged, underwater, submersedWordNet sense 2 (partially aquatic; living or growing partly on land and partly in water):
semiaquaticWordNet sense 3 (operating or living or growing in water):
aquaticFrom the ODE community, based on WordNetadd/edit