WordNet (r) 3.0 (2006):

snorkel
    n 1: breathing device consisting of a bent tube fitting into a
         swimmer's mouth and extending above the surface; allows
         swimmer to breathe while face down in the water
    2: air passage provided by a retractable device containing
       intake and exhaust pipes; permits a submarine to stay
       submerged for extended periods of time [syn: snorkel,
       schnorkel, schnorchel, snorkel breather, breather]
    v 1: dive with a snorkel

Moby Thesaurus II by Grady Ward, 1.0:

81 Moby Thesaurus words for "snorkel":
   Aqua-Lung, Foamite, acid, adjutage, air cylinder, aquascope,
   automatic sprinkler, bathyscaphe, bathysphere, benthoscope,
   carbon tet, carbon tetrachloride, carbon-dioxide foam, catheter,
   deck gun, deluge set, diving bell, diving boat, diving chamber,
   diving goggles, diving helmet, diving hood, diving mask,
   diving suit, drainpipe, efflux tube, extinguisher, fire apparatus,
   fire engine, fire hose, fire hydrant, fireplug, flue pipe, foam,
   foam extinguisher, funnel, garden hose, gas pipe, hook-and-ladder,
   hose, hosepipe, ladder pipe, nipple, organ pipe, periscope, pipe,
   pipeline, pipette, piping, pumper, reed, reed pipe, scuba, siamese,
   siamese connection, siphon, soda, soil pipe, sprinkler,
   sprinkler head, sprinkler system, standpipe, steam pipe, stem,
   straw, submarine, super-pumper, swim fins, tap, tube, tubing,
   tubulation, tubule, tubulet, tubulure, waste pipe, water,
   water cannon, water pipe, wet blanket, wet suit