Its maximum depth is about 7 meters, and it is usually salinity stratified. The deep water of Tarpon Blue Hole is anoxic, highly sulfidic and is very reducing. Nevertheless, life proliferates even under these extreme conditions. Glass fiber filters were used to collect bacteria from the waters of Tarpon Blue Hole. The middle filter is intense red due to anoxygenic, photosynthetic Purple Sulfur Bacteria which abound immediately below the halocline in a zone of high hydrogen sulfide concentration.
Surface water is shown on the left and bottom water on the right.