Definition of subaquatic in US English:

subaquatic

adjective

  • Underwater.

    ‘a narrow, subaquatic microclimate’
    • ‘The reason became apparent once we reached the reef, because on the upper surface no bare rock was visible, just masses of soft coral trees waving in the sub-aquatic breeze.’
    • ‘The sub-aquatic equivalent, these are sharks revving up for a night of frantic hunting.’

Pronunciation