Obviously yoga first comes to mind. I also have started trying some visualization techniques to calm myself down before big races. Calmly sit and with slow breathing just imagine the perfect race. I actually imagine it in slow motion, so that I don't start breathing heavily and get worked up instead of relaxing. Smooth strong swim strokes. Easy transition. Feeling comfortable and confident on the bike. Seeing myself upright and running strong.

The only other thing I usually do is make my packing checklist and triple check it. It gives me something to do to burn off the nervous energy to be able to say "yep, packed the goggles. Yep, packed the gels. Yep, dry shirt to throw on after the race"

Good luck, you'll be great!!!

oooohhh sounds like the aweful taper period anxiety. HATE that! I won't go into any details, but if you are in a relationship, get your partner involved in helping you relax :)

Best of Luck to you--have a fun time!

This is my favorite relaxation set from swim season:

1) Lay down on a comfy bed.
2)Focus on controlled breathing. In through the nose on a count of 4, really fill your lungs. Out through the mouth on a count of six. Slow and controlled.
3) Once you have your breathing under control begin muscle relaxation by tightening/tensing individual muscle groups as you inhale and relaxing them completely as you exhale. I usually start with my toes and work up doing EVERYTHING including my face. I usually will do a muscle group twice before moving on to the next. End by tensing your entire body. When you are done, you should feel warm and like your muscles are melting off your bones.
4) Maintain breathing pattern and begin visualizing. Try not to fall asleep.

good luck!!