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Water in the ocean is generally carried with the mean flow, mixed by eddies, or transported westward by coherent eddies at speeds close to the long baroclinic Rossby wave speed. Modons (dipole eddy pairs) are a theoretically predicted exception to this behavior, which can carry water to the east or west at speeds much larger than the Rossby wave speed, leading to unusual transports of heat, nutrients, and carbon. We provide the first observational evidence of such rapidly moving modons propagating over large distances. These modons are found in the midlatitude oceans around Australia, with one also seen in the South Atlantic west of the Agulhas region. They can travel at more than 10 times the Rossby wave speed of 1-2cms(-1) and typically persist for about 6months carrying their unusual water mass properties with them, before splitting into individual vortices, which can persist for many months longer.

Plain Language Summary The ocean's equivalent of smoke rings has been found. They last for about 6months and can carry water over distances of more than 1,000km in different directions to the usual ocean currents and much faster than other eddies. This changes the way heat, nutrients, and carbon are transported in parts of the ocean. Most eddies drift to the west at or around a particular speed that depends on latitude, faster near the equator, and slower near the poles (about 1-2km/d at midlatitudes). However, it has long been theoretically predicted that eddies can sometimes pair up in a way that allows them, like smoke rings, to travel much faster, to the east as well as west, staying together for a long time. For the first time, using satellite measurements of sea level, we have seen these eddy pairs, called modons, traveling over long distances in the oceans. Eight pairs are seen around Australia and one in the South Atlantic. They travel at about 10 times the typical eddy speed, over distances of 1,000km or more, stirring up the surface temperatures as they pass and lasting for about 6months before splitting up.