During September 1974, ten neutrally buoyant floats were placed in two of the cold eddies spun off from the Gulf Stream. The floats, designed to be neutrally buoyant near the axis of the sound channel, transmit an 80-sec continuous tone with a signal level of 176 dB re 1 μPa every 6 h. These floats have been tracked by the U.S. Naval Oceanographic Office and the positions determined once per day. Since December we have been monitoring the amplitude of the signal at Bermuda on a digital data logger. Approximately, three months of continuous data have been collected and processed. A 15-dB processing gain is achieved by performing a running average over the raw digital data. The data exhibit quasiperiodic variations with a time scale of 300 h. Temperature profiles, collected along the paths between some of the floats and Bermuda, have been used in calculations of transmission loss. Correlations between measured and calculated signal levels are discussed.