Deep under the water off of Florida’s Golf Coast, scientists are exploring a “blue hole,” an ocean cavern that forms below the seabed. While similar to sinkholes that open up on dry land, these mysterious deep wells are often hard to find and difficult to study. Thankfully, tips from local divers and fishermen have led to amazing opportunities to research this phenomenon.
One of the deepest blue holes yet discovered is dubbed the “Green Banana.” Reaching deep into the ocean at a depth of almost 425 feet, this blue hole provides another opportunity for researchers to study the unique chemistry and biology of the cavernous space. In August 2020, a team of scientists plans to head inside the Green Banana in a challenging attempt to catalog another blue hole. (1)
Studying The Mysterious Blue Hole
Dispersed along the undersea continental shelf along Florida’s Gulf Coast, blue holes are unique. Although they can be found around the world, their formation is specific to areas where karst–porous limestone–is present. Because they often open hundreds of feet below the surface, scientists don’t yet know how prevalent or common blue holes are. Openings are also often too small for divers, submersibles, and equipment to fit through for deeper study.
Thankfully, scientists at the Mote Marine Laboratory had the opportunity to study a more accessible blue hole in 2019. Called the “Amberjack hole,” researchers collected a plethora of valuable information about the mysterious space. Water and core samples indicate unique features to these deep underwater oases. From higher levels of nutrients to a possible groundwater connection, there’s much to explore.
The Amberjack hole also contained two dead smalltooth sawfish. While similar in appearance to a shark, these members of the ray family are highly endangered. The two preserved specimens at the bottom of the blue hole add another layer of mystery to these deep water caverns. (2)
A Difficult Dive Into The ‘Green Banana’
Emily Hall is a scientist and program manager at the Mote Marine Laboratory. She’ll be among the team set to explore the Green Banana in August 2020 and May 2021. While deeper than the Amberjack hole, the Green Banana’s formation is hourglass-shaped–which make the dive a bit more difficult. Midway down the hole, things get tight. This narrow section of the hole will be a challenge for dive teams and equipment. “We’re working really hard on trying to come up with the best way to strategically do that and keep everyone safe,” Hall told CNN.
The extraordinary depths also pose a danger to divers. Since the hole stretches so far down, even skilled divers must be careful. The pressure means that divers must rise back to the service slowly to avoid decompression sickness. Diving at 400 feet means it may take 2 hours or more for divers to slowly make their way back up.
Despite the challenges, the team eagerly anticipates the mission. They equate it with the thrill of going to space, where so many unknowns exist. “One of the things that I really love about this mission is that it is exploratory research. We don’t know what we’re going to find,” Hall told CNN. “It’s really neat and exciting to be able to do it.” (1)
