High horizontal resolution data from a tow-yo conductivity-temperature-depth profiling system are analyzed to examine the mesoscale and fine scale response of the Gotland Basin to the 1993 major Baltic inflow. The permanent halocline in the basin is characterized by intensive thermohaline intrusions. A well-defined front of the intrusive region was found to be propagating north from the Stolpe Channel to the Gotland Deep with a speed of 2 cm s-1 or more. A substantial horizontal intermittency of intrusion intensity, related to mesoscale eddies, was observed behind the front. A strongly nonlinear cyclonic eddy, undetectable on the sea surface, was found in the halocline. The cyclone contributed to the transport of salty water after the inflow. The combined effect of the mesoscale eddies and thermohaline intrusions is shown to be one of the mechanisms responsible for the deep water ventilation by major Baltic inflows.¿ 1997 American Geophysical Union