Hidden world of Florida’s underwater caves

Cave diving is always an exhilarating sport. It might seem crazy to want to explore a submerged, underground world, where running out of air means almost certain death. But exploring underwater caves is incredibly exciting. It satisfies the urge to explore the unknown. And it is an eye opening to the way that aquifer’s function. Life on Earth depends on water. While most of the planet’s water exist in the oceans, evaporation separates some water from the salt. When it rains, most of that precious freshwater seeps into the ground. Some soaked up by the roots of plants. But some enters the aquifer, a layer of semi-permeable rock or gravel that holds the water like a sponge. In places where topography goes downhill, the water in the aquifer often flows slowly downhill with it.

Florida has a well-deserved reputation for sun, sand, and ocean. But North Florida is known in the scuba diving community as a top cave diving destination−cave country, as it has the densest collection of freshwater springs collectively discharge billions of gallons of groundwater to the surface. One of the most well-known is the Jug Hole at Ichetucknee Springs State Park. In Florida, the rock beneath the soil is limestone, a soft rock made by coral reef animals millions of years ago when it was a sea floor. Rain falling through the sky picks up carbon dioxide, which creates a very mild acid called carbonic acid. Over thousands of years, this mild acid eats away at soft limestone, eventually hollowing out caves. This turned the aquifer in Florida into underground rivers. Sometimes the river comes close to the surface of the ground, and the ceiling gets thinner until it falls in. In Mexico they call it a cenote. But in Florida, it is called a sinkhole. This gives divers a way into the caves.

Above water, the Jug Hole just looks like a little pond. But underwater, nestled within a ring of eel grass, there is a hole going straight down into the earth. In this part of Florida, the soil is thin over a base of limestone. But over millions of years, rainwater has eaten away at the limestone, creating a Swiss cheese called karst. It is full of caves, which are full of water. In places, the water flows out of the ground in springs that form surface rivers and streams. That is exactly what Jug Hole is−a spring.

Ichetucknee Springs State Park has no less than seven springs that together feed the Ichetucknee River. Jug Hole or also known as the Blue Hole Spring is one of the largest of the springs. It flows between 40 and 60 million gallons of water a day, which is enough to fill two swimming pools every minute. With water gushing out of the Jug Hole, a scuba diver needs to fight to get down into the entrance to the cave since it will blow one back with such force. Once through the narrow opening, divers will enter a large cavern zone that opens like a jug inside, which is where the spring gets its name. With strong currents at the bottom of the jug, the cave leads down at an angle.

Most well-visited caves like this one have a warning sign to remind divers who are not cave trained to stay out. The exceptionally low section of the cave, also called the bedding plane, is wide but noticeably short it barely looks like anyone can fit in there. There was a layer of softer rock in this space, but it was dissolved away by the water, leaving the harder rock on the ceiling and floor. The current through this area is very strong. On the far side of the bedding plane, divers will come out into a larger chamber, and since there is more space, the current is lower. At the far end of the big chamber, the current is gentler, but this is the spot where divers will reach a tiny restriction. Most back-mount divers have to take their scuba tanks off, and not only that, but they also need the right body angle to squeeze through the restriction. Deeper into the cave (about 100 feet deep), the passages are getting smaller. One will find a bone on this cave floor, most likely dating back to a time during the last ice age perhaps 15.000 years ago, when this cave was dry, and animals could walk in here. The end of the line (550 feet from the entrance) is as far as divers can fit in the cave. In this particular area, the water is stagnant and murky.

In the Bahamas and the Yucatan, the caves tend to have a lot of fragile formations, almost no current and salt water under the fresh water. The caves in Florida tend to be all fresh water, often with strong water flow and truly little in the way of ornamentation. Divers do not have to be as concerned about breaking the fragile formations, but they do have to fight the current. It is definitely a different kind of cave diving.

Florida cave systems is a very extensive one, the Peacock Springs State Park in Wes Skiles Florida for example, it spans more than six miles of surveyed underwater passages. The cave systems are also incredibly significant as it contains the fresh water that is the drinking water for everybody. These springs also provide critical habitat for aquatic animals, including the iconic Florida Manatee, also, anchor Florida’s inland water-based recreation industry. Yet, despite its fundamental roles, over the last several decades, a combination of development, population growth, climate change, over pumping of the aquifer and pollution of agriculture and sewage have wreaked havoc on Florida Springs. Many springs show significantly reduced water flow. Others have stopped flowing entirely. The state of Florida officially recognized the problem. In 2001, a legislation is signed creating the Florida Springs Initiative. The program provided the first of several subsequent pools of money for research, monitoring, education, and landowner assistance to reduce the flow of sewage and fertilizer into springs and address declining spring flows. Data collected as a result of the initiative have allowed researchers to track the inexorable decline of Florida’s springs in excruciating detail. Importantly, these data show that efforts to protect springs have so far been ineffective, as nutrient pollution has continued to increase. Clearly, more extensive restoration works need to be done effectively.