Uldolmok is also called Myeongryang (the Crying Sea), because it means 'the sea wails.' It is the narrowest strait between Usuyeong in Haenam-gun and Nokjin in Jindo. It is 325 meters wide, its depth does not exceed twenty meters, and the speed of the current is around 11.5 knots. There are swirling eddies between the winding reefs. It is said that the sound of the sea can be heard as far as twenty 'ri' away, when such rapid currents batter the reefs.

The strait is a natural fortress of specific features not found in any other place in the world. Several times a day, the difference between the rise and fall of the tide amounts to a fathom. The tide gushes in waves white with sea foam. The currents are so violent that large ferries headed for Cheju Island or Wando must wait till the ebb tide to cross the strait.

Such oceanographic features were major contributing factors to the victory over the Japanese invaiders with their four-hundred battleships, in Jeong-yu-jae-ran. Now, the Jindo arch bridge crosses over the wailing sea of Uldolmok.