Seismic profiles from Keene and Smokehouse Lakes show a hard bottom reflection, possibly well sorted sands, infilling a deeper karst surface (type 6, A-A’). The strong bottom reflection leads to multiples seen throughout the data that obscure some of the record. The record is also partially obscured in areas where the lake bottom nears the surface and in areas of topographic lows (gray lines in profiles). This noise could be a result of the accumulation of organic material in the depressions which attenuates the acoustic signal. The acoustic characteristics and their interpretation in the two lakes are similar. Where the record is not obscured, there are numerous small low angle reflections with high-angle reflections dipping toward their center, where the record is obscured (profiles, type 1). Concentric reflections extend to depth in the profile. These features may represent solution pipes or small subsidence into the karst subsurface, which is in close proximity to the surface in this area. This condition has a high potential for increased leakage. The distribution of these features (red outline, Distribution of Features) shows that they are small and trend along the periphery of the bathymetric lows of the lake (blue line, Distribution of Features). Other lakes surveyed in The Gap show that the subsurface features better define the bathymetric lows in the lakes (Lakes Trout, Hammond, and Dixie).