Samples of seawater from the Indian Ocean (RRS DISCOVERY Sts. 5102-5206) and the Arabian Sea (Sts. 5077-5094), obtained in 1962 through 1964 with N.I.O. sampling bottles, have been analyzed for Mn, Co, Cu, Fe, and Zn. This investigation has indicated that, in the northwestern Indian Ocean and the Arabian Sea, higher values of these trace elements are found in the surface layers compared with the bottom layer and that there is a tendency for these trace elements to decrease in concentration with depth....