New magnetic anomaly identifications for the central part of the Cocos plate and the corresponding part of the Pacific plate indicate a pulse of extremely rapid seafloor spreading in the middle Miocene, about 11--18 Ma, possibly beginning as early as 25 Ma. The spacing of anomalies 5A--5D indicates a full spreading rate for the southern Cocos-Pacific boundary of 180--210 mm/yr, depending on the choice of time scale. Relative to the maximum 0--3 Ma spreading rate of 152 mm/yr, this result significantly expands the upper limit of well documented rates. ¿ American Geophysical Union 1996