Current meter data on the northern slope of the island of Tahiti show the presence of internal waves principally at diurnal, inertial and sub-inertial frequencies. The amplitude of these internal waves is sufficient to bring nutrient-rich water to 30 or 40 m depth. This is the elevation of the base of the spur-and-groove system of coral reefs. From there the nutrients can readily be brought to the surface by wave-driven-upwelling in the grooves. The coupling of internal waves and upwelling in grooves on coral reef slopes may account for the elevated productivity of the coral reefs in oligotrophic surface oceanic waters.