Buoyant

Buoy·ant

Buoyant

a.
  1. Having the quality of rising or floating in a fluid; tending to rise or float; as, iron is buoyant in mercury.
  2. Bearing up, as a fluid; sustaining another body by being specifically heavier.
    The water under me was buoyant.
  3. Light-hearted; vivacious; cheerful; as, a buoyant disposition; buoyant spirits.