Lulunew2scub:
I am new to scuba and just finished my 2nd confined water dive tonight and can't figure out why my calves keep cramping...
You aren't necessarily doing anything wrong. You use different muscles when you kick, and you've added a lot of resistance to the activity (water and fins). There are different ways to accomodate this.
1. Stregthing muscles: More dives (or a new workout routine) will strengthen your calf and other leg muscles. If you dive regularly, you'll see a change in your leg stregth & work tolerance. Also, make a pre-dive stretch (slow stretch, not bouncy) part of your routine to warm-up your leg muscles.
2. Resting muscles: Add alternative kicks. Watch veteran divers and you'll see that many use different kick styles. Alternating your standard flutter kick with other kicks will rest the calves and work other muscle groups. Also, you'll be amazed at how a good breathing pattern will help resolve muscle tension. Exhale deeply, breath slowly.
3. Decreasing resistance: The suggestion to use split fins is one way of decreasing the resistance during the kick, but there are disadvantages to this. Because splits move the water off your foot differently than non-splits, they do not provide the stronger powerkick that a diver might need on occasion. In a strong current, they won't provide the same propulsion as a good pair on non-splits. Another way to reduce the resistance is to find fins with a different blade - not just a softer blade (you're back to sacrificing power in a current if you use too soft a blade). But look at the many fin designs, and you'll see differences in the way water is channeled off the blade, increasing or decreasing fin efficiency. The foot pockets of many fins also differ, and the stiffness is another variable. The previous suggestion on testing out different fins is a good idea. (Beware the bells & whistles - lots of marketing goes on to sell some silly stuff.)
4. Feed your muscles: Muscles that are well hydrated work better. Muscles that are well fed work better. A bottle of water and a banana won't create miracles, but they help. Nutrition is a long term thing, but combined with alternate kicks, predive stretching, frequent dives (or exercises), and good fins, your leg cramps should resolve on future dives.
Enjoy your dives!!!