The southwest area consists of a broad flat bottom with a bathymetry very similar to that in the southeast and north areas, except for the collapse sinkhole (type 5, D-D’) near the southwestern shore. The sinkhole has completely breached the confining unit. It is possible that other features are present but access was limited by aquatic weeds and the southwest area could not be completely surveyed.

The clustered collapse sinkholes are near the southwestern shoreline adjacent to Heagy-Burry Park and boat ramp. Observations by scuba divers indicate that there is a downward flow of water from the lake into one of the sinks (Spechler and Wilson, 1992). Reports by Pirkle and Brooks (1959b) and Spechler and Wilson (1992) indicate a direct hydraulic connection with the aquifer. During the 1956 drought, water from Orange Lake could be seen draining into the collapse sinkhole of Heagy-Burry Park. Profile D-D’ shows the steep slope and fault blocks of the sinkhole. The mass movement of limestone blocks would open pathways for water to migrate along the fractures. Sediment slumping along the steep flanks of the sinkhole also are visible and are part of the natural process that plugs the doline. Adjacent to the collapse are evidence of adjacent cover subsidence sinkholes that ultimately may coalesce in the sinkhole complex.