Observational Program. En route from San Francisco 

 to Pearl Harbor several types of observations were made 

 while the USS NEREUS was underway. These observations 

 included bathythermograph lowerings made hourly throughout 

 the entire passage; descriptions of sea surface characteristics 

 made three times a day; and notations of the sea, swells, 

 slicks, and all visible biological life. 



En route from Pearl Harbor to Adak new types of ob- 

 servations were made in addition to the bathythermograph 

 lowerings and surface characteristic descriptions. Complete 

 weather data were taken. The fathometer was run continu- 

 ously at high gain to detect the deep scattering layer. Once 

 each morning the ship hove to in order to drop six SOFAR 

 bombs to test the sound transmission. During these stops 

 a plankton net haul was taken. 



North from Adak the hourly bathythermograph and surface 

 observations were continued until the 100-fathom contour was 

 reached. At that time a more detailed program could be 

 accomplished. In the shallow depths of the Bering and Chukchi 

 Seas the USS NEREUS hove to four times a day at 0300, 0900, 

 1500 and 2100 LCT for a period of approximately one hour. 

 During this time the following measurements were taken: 

 (1) a bathythermograph lowering to the bottom, (2) a vertical 

 series of simultaneous temperature and water samples, (3) a 

 snapper sample of the sea bottom, (4) a core of sediment of 

 the sea bottom, (5) a sea floor photograph, when possible, 



(6) a transparency measurement by means of a Secchi disc, 



(7) a plankton net haul through the water from bottom to 

 surface, (8) an ambient noise measurement, and (9) surface 

 observations including weather, waves, swell, ice, water 

 color, phosphorescence, birds, whales, fish, etc. This pro- 

 gram continued until the pack ice was reached. 



In the pack ice the USS NEREUS hove to for 24 hours, 

 during which time repeated bathythermograph observations 

 were made every 30 minutes. Vertical series of water sam- 

 ples and temperature were taken every six hours. A small 

 boat cruise was made eight miles farther into the pack ice 

 to sample the bottom under more dense ice. 



On the return cruise from the ice region to Norton Sound, 

 four stops were made daily, and the same observational pro- 

 gram was followed as on the northern passage. Five additional 

 stations were occupied across the Alaskan side of.Bering 

 Strait. 



From Norton Sound to Unimak Island only surface observa- 

 tions could be taken because search operations for a lost plane 

 near Unimak prevented any stops. On the southern side of 



