Home  >  Magazine  >  Issue 36 : Sep/Oct 2010  > Columns  >  High Tide  >  Kuroshio


High Tide

By Mitsuharu Kume




There is a 100-kilometer-wide road. Did you know about this road? It would be impossible on land, so, we’re talking about a road in the ocean.

It’s known as the Kuroshio, or Black Current, and it flows from the South China Sea, through Kagoshima’s Tokara Islands and into the Pacific, along the coast of Japan to the northeast, past the Boso Peninsula in Chiba, then to the north and east. The Kuroshio is the largest ocean current in the world. 

This 100-kilometer-wide road carries many things with it. Some are what you would expect coming from the southern hemisphere, such as coconuts, but there is also a lot of garbage drifting along with it. At the large end of the spectrum, even ships can be carried away on the Kuroshio. On these ships, there can be people whose culture is also riding the current. 

Along the Pacific Coast, the water is always flowing, so it is easy to think of it like an escalator or a moving walkway.

The top speed of the current is about four knots, or 7.4 kph. That’s about the same as a person moving at a fast walking pace or a half-trot. But what is it really like? I am checking it out right now.

I am on a sailboat traveling from island to island, from Kagoshima to Amami Oshima, photographing umegame, the common murre or guillemot, and at this writing, I am right on top of the Kuroshio. 

The current is always changing and becoming more complex as it passes between islands; the speed changing as the flow just keeps going along. The Kuroshio will also stay in one place for three or four hours, due to the pull of the tide. It’s kind of like knowing the wind; it’s important to understand the flowing of the water below you.

There is that old Japanese saying to which I often refer—“Age shio ja, age shio ja”—literally, “The tide is rising,” which also means things are moving in the right direction. For me, it is a rising tide right now. For an island nation such as Japan, since ancient times this rising tide has been linked to people’s lives. 

The attraction of the moon, the subsea topography, the rotation of the earth—all factors involved in the pull of the tide. There are many factors in nature that are involved in creating a good balance, and the Kuroshio is formed in the same way. 

As I’m swaying along in the Kuroshio, I am acutely aware the ocean is liquid, but the whole idea still moves me. I think to a time when I was surrounded by fluid inside my mother. Was it similar to this? I kind of think so. 

All I know is, I sleep really well when I’m on the sailboat. I have to be careful not to sleep in too late tomorrow…