Which current flows ceaselessly without ever encountering a landmass?

The Southern Ocean surrounds the continent of Antarctica. The major current of the Southern Ocean is the ACC--the Antarctic Circumpolar Current. It is the only current in the world's oceans that flows without ever encountering a land mass. It moves more water than any other current, and flows through parts of three other oceans--the Atlantic, Pacific and the Indian. Although the ACC does not directly encounter land, it is influenced by both the continent of Antarctica and the southern portions of South America. For example, the area between Cape Horn and the Antarctic Peninsula is much narrower compared to the area occupied by the ACC around the rest of Antarctica.

A great deal more information including average temperature, depth, and the history of early exploration and discovery of the ACC can be found in the first attached link. The second link is from the same source, and has information about all the ocean currents.