During the 26th cruise of the Research Vessel Varuna, the Palk Bay has been covered from 18th to 20th March, 1963. The location of the Stations (Nos. 1631 to 1681) occupied during this cruise are shown in Fig. 1. The Bay is a very shallow and flat basin, nowhere exceeding 15 metres deep. On an average its depth hardly exceeds 9 metres. Temperature, salinity and dissolved oxygen are the parameters of which the data have been collected during the cruise. Samples were taken from the surface at every station and from 5 metre depth at many stations and also from 10 metre depth at a few stations depended on the sonic depth of the station. These data have been used for bringing out the hydrographic features of the Palk Bay. The prevailing winds are also considering in the analysis, the relevant wind date being taken from the daily weather reports of the Indian Mateorological Department. The Palk Bay is divided into four different zones based on the nature of the data collected and the distributions of different parameters in these four zones are also presented.