The hydrographical conditions founded in Port Foster (Deception Island) and Chile Bay (Greenwich Island) both belong to the South Shetlands Islands group, Antarctic Peninsula, has been described. This survey has been carried out from the Chilean Navy Oceanographic vessel "YELCHO" in January 1978. An stratification in the area closed with the Antarctic surface waters has been observed. The temperature ranged between -1,60 º C to 1,30º C in Port Foster and 0,46ºC to 1,70ºC in Chile Bay; the salinity ranged between 33.80 to 34,24 in Port Foster and 33,61 to 34 in Chile Bay; the dissolved oxygen varied between 3,47 to 7,02 ml O2/l in both area. The characteristic density (Sigma t) of Antarctic Surface waters in the area, i.e., 26,92 and 27,58 has been observed.
