The main armada—six aircraft carriers (Akagi, Kaga, Sōryū, Hiryū, Shōkaku, Zuikaku) plus battleships, cruisers, destroyers, and oilers—sailed from Hitokappu Bay in the Kuril Islands (northeast Japan) on November 26, 1941, maintaining strict radio silence and navigating north of Midway to avoid detection.
They covered roughly 3,500–3,850 miles (about 6,200 km) to reach the launch zone located approximately 230 nautical miles (≈265 miles / 426 km) north of Oahu between December 6–7. The fleet included eight oilers to enable mid-ocean refueling, a relatively new capability for the Imperial Japanese Navy.
On the morning of December 7, carriers were positioned about 230 nautical miles north of Oahu. Strike aircraft (e.g., Nakajima B5N “Kate” torpedo bombers) flew roughly 250 miles over open ocean to reach Pearl Harbor—about a two-hour flight
