The prewar sea route to the north coast of New Guinea, particularly the Buna area of planned operations, had been closed by the Japanese advance and naval control of open waters leaving only an inshore route described by MacArthur's Chief of Transportation, as "the most dangerous coastline in the world" and essentially uncharted. In October 1942, all the vessels of the US Army Small Ships Section, largely crewed by Australians, had been ordered to Milne Bay to support the operations against Japanese in the Buna area. Those small vessels, in their night runs to Oro Bay, had begun noting channels and marking reefs with oil drums. The small ships could not support the beachhead, being largely supported by air, with heavy equipment and supplies so that a way for large ships had to be found.