AUGUST–34°42′ N. 140°19′ W

In the middle of the night, I dream that I am at the wheel of a great ship, sailing the Pacific Ocean. The cold air is thick with moisture. The rigging creaks with the roll of the ship. Water hisses along the lee rail.

In the afternoon, Mary told us that we had passed the NOAA waypoint. It had gone by without fanfare, earlier that day or the previous night. Aside from the debris watch, no measurements were taken that I knew of. We had found no mother lode there, and so had moved on, setting course for the University of Hawaii waypoint.

The water, choppy and gray, was free of trash. We appeared to be having trouble finding not only a good stretch of garbage but also the North Pacific Subtropical Gyre itself. We were sailing on strong winds, which suggested that the high‑pressure zone that is associated with the Gyre was farther west than usual. Would we never get to sail the seas of plastic? Mary maintained that there was trash in the water here, but that we couldn’t see it because it had been pushed below the surface of the water by the increased wind and higher waves.

Nikolai Maximenko, the University of Hawaii oceanographer with whom Mary was working, later confirmed for me that this effect exists. But it was also increasingly apparent that day that the Garbage Patch was anything but uniform. It varied from spot to spot, heterogeneous and changing.

But that didn’t matter. What mattered was getting farther west while we still could, and finding more trash.