Before Ocean Drilling Program (ODP) Leg 166, there were very few direct geothermal measurements in offshore Florida-Bahama carbonate platforms. There has been no report of measurements using conventional marine heat-flow probes such as those described by Bullard (1954), Jemsek et al. (1985), and Lister et al. (1990). This is probably because of the difficulty associated with determining geothermal heat flow in a shallow-water environment. Much of the seafloor in the Straits of Florida is shallower than 800 meters below sea level (mbsl). There is significant seasonal fluctuation in the temperature of the bottom seawater (e.g., Niiler and Richardson, 1973). Normally, a geothermal probe penetrates only 5-7 meters below seafloor (mbsf), while the thermal noise associated with the seasonal fluctuation may penetrate deeper than 10 mbsf. Some borehole temperature measurements were reported offshore of southwestern Florida (Buffler et al., 1984), but the Bahama platform was virtually "untouched." The in situ bottom-hole temperature data from Leg 166, which were obtained in depths of 30-300 mbsf, may provide the first direct information on the thermal regime of the platform.