A current meter mooring was deployed for one year at the mean position of the Gulf Stream at 68 ¿W. With instruments from 400 m to 4000 m, it provides the first unambiguous evidence that the Gulf Stream extends from top to bottom of the water column. Using the strong cross-stream temperature structure to derive a horizontal coordinate related to temperature, we estimate the width and transport of the Gulf Stream for four individual events and we determine an average profile of the vertical and cross-stream structure of the Gulf Stream. A conservative estimate of transport for this average profile indicates that the Gulf Stream has a transport of 103¿106 m3 s-1 at 68 ¿W.