Tidal phenomena in the Indonesian seas are among the most complex in the world. Complicated coastal geometries with narrow straits and myriad small islands, rugged bottom topography next to wide shelves of shallow water, and large quantities of tidal power input from the adjoining Indian and Pacific Oceans—all combine to form a complex system of interfering three-dimensional waves. The seas feature multiple amphidromes (points in the sea where there is zero tidal amplitude due to canceling of tidal waves), strong tidal currents, residual circulations, internal waves, and solitons. Diurnal tides are unusually strong and are dominant along some coastlines. The tides are known to affect local mixing and circulation, but the tidal energy available for these processes is not yet reliably determined. And while mapping of the Indonesian tides has benefited markedly by assimilating satellite altimeter measurements into numerical models, improvements to the energy budget will likely require higher-resolution analyses and a densified network of satellite tidal measurements.