Modified fin kicks are another adaptation divers must make when entering a cave environment. Cave and cavern divers rarely use the full flutter kick because it produces too much turbulence directed toward the bottom. Cave and cavern certification courses typically cover two alternative kicks:
Frog Kick. The most common modified kick is the frog kick, which is accomplished by spreading the legs, rotating the fins so that the bottom of the fin blades come as close to facing each other as possible and then bringing the fins together, forcing water from between the two blades.
This kick isolates nearly all of the thrust and water turbulence to the area immediately behind the diver and requires a good deal less energy than a standard flutter kick.
In addition to increasing endurance and decreasing air consumption, the frog kick also provides another interesting benefit--you'll swim straighter. Most divers tend to drift slightly right or left as they flutter kick because one leg is slightly stronger than the other. Using the frog kick, the majority of all thrust comes from between the fins and directly behind the diver, which minimizes drift.
Modified Flutter Kick. This kick is accomplished by bending the knees slightly and shortening the stroke of the kick. When done properly, all fin movement takes place above the center of the body, minimizing water movement below the body.
After the cavern diver masters the new finning techniques, he'll learn how to utilize the fins to rotate his body with minimal disturbance of the water column. When mastered, this skill will allow the diver to utilize one fin to rotate his body on a point very close to the body's center.
When all the skills are combined, the well-trained cavern diver can swim, manage a light and a reel, keep track of his buddy without touching the cavern walls or disturbing its silt-laden bottom. Mastering these skills literally opens a new world to the recreational diver--a world of unique and beautiful geology unlike any other in diving.
Even if exploring caves and caverns isn't your idea of underwater fun, a cavern course conducted by a qualified instructor will equip you with useful skills for better open-water diving.
If you think back to your last few dive trips, you will probably remember seeing a cavern diver. He was the diver who stepped off the boat, descended slowly and efficiently to the bottom, never making contact, turned effortlessly into a proper swimming position and moved just as effortlessly through the entire dive. He never damaged the bottom with a touch or an erratic fin kick and his fins never disturbed a single grain of sand. These are the marks of the diver who has mastered buoyancy control, one of the essential skills in cavern exploration. If better buoyancy is your goal, a cavern course is a good place to learn it.