Temperatures were recorded with Watanabe deep-sea reversing 

 thermometers obtained from the Philippine Coast and Geodetic Survey. 

 The caHbration certificates for these thermometers were not available 

 so they were calibrated by comparison with two Richter and Wiese 

 thermometers. The certificates for these two reference thermometers 

 also are not available at present. Therefore the temperatures reported 

 here are only relative. The exact absolute values must await the 

 calibration of the reference thermometers. Corrections to be applied 

 will not be of great magnitude, and such corrections are not expected 

 to alter the general picture of the distribution of temperature and density 

 as computed from " Baird " data. A comparison of the " Baird " 

 temperatures with those of the " SnelHus " for the deep water of the 

 Sulu Basin show very good agreement. Therefore it seems justifiable 

 to report conditions now even though there are slight errors in the 

 absolute values. 



Acknowledgments 



The oceanographic work of the Philippine Fishery Programme was 

 planned and supervised by Herbert E. Warfel under the administration 

 of Hugh W. Terhune. In the planning phase John Lyman and Richard 

 Tibby acted as advisors. The collection of data in the field was under 

 the direction of Joseph Goodman and Ralph Jentoft, while William 

 Wood was in charge of the reduction and analysis of data. Much of 

 the routine computation was made by Teodoro Megia. Alfonso Sebastian 

 and Bonifacio Dionisio also assisted in the computations and graphical 

 presentation of data. Fabian Magpile prepared the finished charts 

 and graphs. The chemical analyses of water samples were made by 

 Mr. Ricardo Lao, Manuel Llorca, and Manuel Ciocon, under the direction 

 of Dr. Goodman and Mr. Jentoft. 



The Sulu Basin 



The Sulu Sea has a maximum depth of 5,576 metres, and over a 

 large area is over 4,000 metres deep. Chart 1 shows the outstanding 

 features of the bottom topography. The 4,000-metre and 2,000-metre 

 contours are shown throughout. The stippled area indicates depths of 

 less than 200 metres. The 100-metre and 500-metre contours are drawn 

 only at critical points. The main purpose in presenting this chart is 

 to indicate the nature of the communications which exist between the 

 Sulu Sea and adjacent waters. It is evident that the Sulu Sea is con- 

 nected with surrounding seas only over shallow sills or through narrow 

 troughs. 



The surface waters are in communication with the South China 

 Sea to the west through Balabac Strait, which lies between Palawan 

 and Borneo, and to the north by way of Mindoro Strait west of Mindoro. 

 Communication with the open Pacific is by way of various straits between 

 the southern Philippine Islands to the east and by way of the Celebes 

 Sea to the south through the Sulu Archipelago. 



All these communications with outside waters are restricted to upper 

 water layers. The shallowest of the connections is to the east. Although 

 deep water connects the Sulu Sea with the Mindanao Sea (between 



228 



