He was anxious to verify the existence of a certain island, Karafonto, Tchoka, or Chicha by name, set down as between Yezo and Saghalien in a map which appeared at St. Petersburg in 1802, and was based on one brought to Russia by the Japanese Koday.

He then surveyed a small portion of the coast of Yezo, naming the chief irregularities, and cast anchor near the southernmost promontory of the island, at the entrance to the Straits of La Pérouse. Here he learnt from the Japanese that Saghalien and Karafonto were one and the same island. On the 10th May, 1805, Kruzenstern landed at Yezo, and was surprised to find the season but little advanced.