The ice encountered during the period 1 to 6 August was 

 in a state of melting, with rotten ice in all areas between 

 71°50'to 72°45'N and 161° to 160OW. The southern limits of 

 ice in the summer of 1947 were farther north than usually 

 observed, thus permitting navigation to about 72°N at these 

 longitudes. 



Transparency of the sea water was less than that observed 

 in the open sea; however, it was greater than found in coastal 

 regions, with an average Secchi disc reading of 30 feet ob- 

 served in the Bering and Chukchi Seas. The regions of greatest 

 transparency were found in the north central portion of the 

 Bering Sea and north of 69°N in the Chukchi Sea. 



Ambient noise throughout the areas was very low. Equip- 

 ment limitations and ship noises prevented the establishment 

 of exact levels. Near shore, surface noises were audible. In 

 the melting ice, low sounds of rushing water were heard with 

 an occasional splash. No biological noises were heard. 



Two types of biological observations from the arctic 

 region are reported here. One is the deep scattering layer 

 (believed to be biological in nature); the other is the zoo- 

 plankton obtained by net hauls. The observations of the deep 

 scattering layer, the first ever reported in the Bering Sea, 

 were picked up on the NEREUS' recording fathometer. It 

 was first observed in the deep channel north of Adak, sepa- 

 rating from the outgoing ping at 75 fathoms in the early hours 

 of the morning daylight and reaching about 100 fathoms by 

 early afternoon. It remained at this unusually shallow depth 

 until the continental slope was reached. No scattering layer 

 could be recorded on the continental slope. 



The vertical zooplankton net hauls taken throughout the 

 Bering Sea verified species and abundance of plankton found 

 previously by the CHELAN in this area. Although this is the 

 first extensive plankton sampling undertaken in the Chukchi 

 Sea, practically all species found in the Bering Sea were also 

 found near the southern limits of ice; however, many Chukchi 

 Sea species were not found in the Bering Sea. This is sig- 

 nificant since it shows that Bering Sea water flows through 

 the Bering Strait to the ice pack. 



