Compelling and ambiguous, this underground pool house is experienced as an apparition in the landscape along the coast of the sound. Set into a subtle incline just before the land drops off to meet the water’s edge, it is almost invisible as one approaches from the main entrance. From this point of arrival, the only hint of what lies below is a series of glass skylights cut into the ground. The structure faces the sound through full-height glass walls that bring daylight into the interiors and retract to give access to a terrace that is shaded by a brise-soleil. The central interior space is clean, minimalist, and unoccupied except for the 75-foot-long lap pool with a floor-to-ceiling glass wall at one end to provide a transparent barrier between the pool environment and the studio. The supporting elements and fitness areas are nestled into the landscape behind the rear wall of the pool. Anchored in the rolling hills, a 35 foot cantilevered structure spans the width of the pool, expressing its structure with thin corian beams which disappear into a thin trellis beyond. Air temperature and pool water temperature are both controlled by a closed loop geothermal heating and cooling system. The building is also passively warmed by a south-facing glass wall protected by a fixed trellis. The vegetated green roof absorbs rain water and excess heat to avoid overheating of interior spaces.