There are hundreds, if not thousands, of sink holes across the ocean floor. Scientists call them “blue holes,” and right now, they are focused on one in particular called the Green Banana.
The Green Banana, named in the 1970s after a boat captain saw a green banana skin floating nearby, is one of the deepest blue holes ever discovered. Located 155 feet below the ocean’s surface off St. Petersburg, Florida, it extends approximately 275 feet into the ocean floor. Scientists hope to discover if it connects with other sink holes and if there is freshwater inside.
The water inside blue holes is often unusually clear, making for good diving, and because of the unique ocean chemistry, fish, sponges, and plants flourish inside. They are difficult to spot from above, however, so while scientists have verified approximately 20 sink holes on Florida’s West coast, they estimate that there are probably twice that number.
Blue Holes often have narrow entry points and broaden out inside, making it impossible for submersibles to enter. During the mission to enter the Green Banana next month, which is funded by NOAA, scientists will lower a 600-pound lander into the hole to collect water and sediment samples and complete a biological survey.