The Atlantic and Pacific Oceans meet in a dramatic clash of blue, and a viral video claims they never mix—but that sharp dividing line is not what it seems. At the Gulf of Alaska, swirling currents

Look at a map of the world’s oceans, and they appear as one continuous, connected body of water. But out on the open sea, in certain locations, something strange happens. Two massive bodies of water collide—and refuse to mix. A visible, sharp line cuts across the surface, running for miles like an invisible border or a transparent wall. On one side, the ocean is a deep, dark blue. A few meters awa…