There were several reasons why Admiral Yi decided on this location for battle. Myeongnyang Strait had currents, eddies, and whirlpools so powerful that ships could only enter safely a few at a time. The north-south tidal flow reversed every three hours, limiting the time that the Japanese could mount an offensive. The strait was sufficiently narrow that it would prove impossible for the Japanese to flank or envelop the numerically inferior Joseon fleet. The deep shadows of the surrounding hillsides provided the Joseon ships with concealment. On that particular day there was also a heavy mist, dramatically reducing visibility in favor of the Joseon fleet. Therefore, despite being vastly outnumbered, Admiral Yi used the terrain restrictions to neutralize the Japanese navy's staggering numerical advantage.