In the Kii Channel, a weaker phenomenon similar to the kyucho sometimes occurs. Takeoka (1996) inferred that the difference between the kyucho in the Bungo and Kii Channels is due to the basic structure of the Seto Inland Sea. Since the water depth is shallower and the river runoff larger in the eastern section than in the western one, the water density decreases in the eastern part during the summer period. Therefore, the density contrast between the Kuroshio and the coastal waters decreases in the Kii Channel, resulting in weaker and less frequent kyucho in the Kii Channel.