Vortex Spring is a cold, freshwater spring that produces approximately 28 million US gallons (110,000 m3) of water daily. The spring consists of a 200 ft (61 m) basin with sloping sides and an underground cave which links the spring to the Floridan aquifer. Water temperature is steady at 68 °F (20 °C) with no thermocline, and is typically very clear. The spring runoff flows into nearby Otter Creek, which joins Sandy Creek a short distance upstream of Ponce de Leon Spring. There are many fish in the spring; large carp swim in the basin while freshwater eels live in the cave. The cave has been measured to a total of 1,642 feet (500 m).
Vortex Spring is a popular diving area both for experienced and novice divers. Dive training is offered at the park. There are two underwater training platforms at 20 feet (6.1 m) which are often used for Open Water certification dives, and a "talk box" that divers swim into, allowing them to talk to each other while under the surface. The cavern entrance is at 58 feet (18 m) below the surface, and has an opening of 9 by 12 feet (2.7 m × 3.7 m). A handrail is mounted along the wall of the cave. The cave is accessible to 310 feet (94 m), further passage is blocked by a steel grate. Experienced divers are allowed to dive to 115 feet (35 m).
At the site, many facilities are provided for visitors. A restaurant, lodging, dive shop, and changing rooms with heated showers are on site. Recreational features include diving boards, rope swings, and slides into the swimming area. Camping facilities, picnic areas, a basketball court, volleyball court, paddle boats, floats, and canoes are also provided.
The cave has been a controversial aspect of the spring. During the early 1990s, 13 divers died exploring it. The state threatened to ban diving near cave entrances; divers responded by developing a cave diving certification and erecting a locked gate to bar entrance to all but those who had earned it.
In 2010, Ben McDaniel, a diver who had apparently been exploring the cave by surpassing the gate due to his lack of cave certification, did not resurface after an employee let him through it one evening. It was initially assumed that he had died, but extensive searches did not find his body or any sign that one was present, just some oddly placed and filled air tanks. It has been speculated that his body was disposed of somewhere else, that he was murdered (especially after the similarly suspicious death of owner Lowell Kelly late the following year) or that he even staged the disappearance to start a new life free from the many personal problems he had been having. In 2012, another diver died in the cave, believed by those who recovered him to have been motivated by a reward offered by McDaniel's parents, which they rescinded afterwards.
- Montgomery, Ben (April 15, 2011). "When a diver goes missing, a deep cave is scene of a deeper mystery". Tampa Bay Times. Retrieved July 23, 2015.
- Wolff, Cindy (February 19, 2012). "Theories about Collierville diver's disappearance swirl in vortex of unanswered questions". Memphis Commercial Appeal. Retrieved July 23, 2015.
- Wolff, Cindy (April 14, 2012). "Collierville parents pull reward for missing diver". Memphis Commercial Appeal. Retrieved July 25, 2015.