WordNet (r) 3.0 (2006):

swan dive
    n 1: a dive in which the diver arches the back with arms
         outstretched before entering the water [syn: swan dive,
         swallow dive]

Moby Thesaurus II by Grady Ward, 1.0:

22 Moby Thesaurus words for "swan dive":
   belly buster, belly flop, belly whopper, cannonball, crash dive,
   dive, drop, fall, gainer, header, jackknife, nose dive,
   parachute jump, pitch, plunge, pounce, power dive, running dive,
   sky dive, stationary dive, stoop, swoop