213-215Degree of saturation of calcium carbonate as a function of depth has been studied at 3 locations in the Indian Ocean from alkalinity and pH measurements. Surface waters are 4-5 fold supersaturated with respect to calcite. Degree of saturation is maximum within the first 50 m. As the depth increases, the degree of saturation decreases and at about 1000 m the waters become either undersaturated or near-saturated