Internal wave measurements from moorings and profiling floats throughout the Philippine Archipelago, collected as part of the Office of Naval Research Philippine Straits Dynamics Experiment, reveal a wealth of subsurface processes, some of which have not been observed previously (in the Philippines or elsewhere). Complex bathymetry and spatially varying tide and wind forcing produce distinct internal wave environments within the network of seas and channels, ranging from quiescent interior basins to remotely forced straits. Internal tides in both the diurnal and semidiurnal bands dominate much of the velocity structure and are likely the dominant source of energy for mixing in the region. In addition, the transfer of energy from the internal tide directly to near-inertial motions through parametric subharmonic instability appears to be active and, rather than wind forcing, is the dominant source of near-inertial band energy.

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