INTRODUCTION 



Following the purchase of the bathyscaph TRIESTE by 

 the Office of Naval Research in the spring of 1958, the 

 vehicle was transported to the U. S. Navy Electronics 

 Laboratory, San Diego, California. Reassembly of the 

 craft was accomplished at the Naval Repair Facility, San 

 Diego, by early October 1958. 



The first dive of the TRIESTE in the Pacific was made 

 on 2 December 1958 off Point Loma, San Diego. The 

 diving schedule was then interrupted by a modification 

 program which included the acquisition of a new sphere 

 designed to permit safe dives to 36, 000 feet. All dives 

 made in the spring (Nos. 51-56) and fall (Nos. 57-58) of 

 1959 were performed to test and evaluate the modified 

 float, hardware, and equipment to be utilized in the 

 Marianas Trench dives. 



Project NEKTON I, a series of dives in the vicinity of 

 Guam, began in 1959 and continued into early 1960. This 

 series yielded three new depth records for a manned 

 vehicle- -a technological breakthrough of significant im- 

 portance- -plus the acquisition of valuable environmental 

 data. 



Project NEKTON II dives, which were also conducted 

 in the Guam area, took place during June and July 1960. 

 These tests were concerned with: 



1. Precise determination of the velocity of sound 

 throughout the maximum water column. 



2. Determination of the temperature and salinity 

 structure of the water column. 



3. Water- current measurements. 



4. Light penetration, water clarity, and biolumines- 

 cent measurements. 



5. Observations of the distribution of organisms in 

 the water column and on the sea floor. 



6. Marine geological study of the trench environment, 



7. Engineering tests of equipment at great depths. 



Subsequent to the dives of NEKTON II in July 1960, 

 the TRIESTE underwent an extensive period of modification, 

 refitting, and rebuilding in preparation for further research 

 studies. 



