[1] An episode of subtropical water intruding in the tropical waters north of Madagascar during the austral summer of 2001 is documented by a combination of satellite derived surface chlorophyll and sea surface height observations and simultaneous in-situ observations of velocity, chemical and biological tracers. A westward jet clearly of subtropical origin is found in the Comoros basin as a continuation of the South Equatorial Current. Further west, a strong anticyclonic Mozambique eddy is formed north of the narrows, that propagates southward into the Channel. The phenomenon documented here seems to occur each austral summer, and may be part of the adjustment to the seasonal variations in the wind forcing over the subtropical and tropical gyres.