The Collaborative International Dictionary of English v.0.48:

Dive \Dive\, v. i. [imp. & p. p. Dived, colloq. Dove, a
   relic of the AS. strong forms de['a]f, dofen; p. pr. & vb. n.
   Diving.] [OE. diven, duven, AS. d?fan to sink, v. t., fr.
   d?fan, v. i.; akin to Icel. d?fa, G. taufen, E. dip, deep,
   and perh. to dove, n. Cf. Dip.]
   1. To plunge into water head foremost; to thrust the body
      under, or deeply into, water or other fluid.
      [1913 Webster]

            It is not that pearls fetch a high price because men
            have dived for them.                  --Whately.
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   Note: The colloquial form dove is common in the United States
         as an imperfect tense form.
         [1913 Webster]

               All [the walruses] dove down with a tremendous
               splash.                            --Dr. Hayes.
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               When closely pressed it [the loon] dove . . . and
               left the young bird sitting in the water. --J.
                                                  Burroughs.
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   2. Fig.: To plunge or to go deeply into any subject,
      question, business, etc.; to penetrate; to explore.
      --South.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Diving \Div"ing\, a.
   That dives or is used or diving.
   [1913 Webster]

   Diving beetle (Zool.), any beetle of the family
      Dytiscid[ae], which habitually lives under water; --
      called also water tiger.

   Diving bell, a hollow inverted vessel, sometimes
      bell-shaped, in which men may descend and work under
      water, respiration being sustained by the compressed air
      at the top, by fresh air pumped in through a tube from
      above.

   Diving dress. See Submarine armor, under Submarine.

   Diving stone, a kind of jasper.
      [1913 Webster]

WordNet (r) 3.0 (2006):

diving
    n 1: an athletic competition that involves diving into water
         [syn: diving, diving event]
    2: a headlong plunge into water [syn: dive, diving]

Moby Thesaurus II by Grady Ward, 1.0:

53 Moby Thesaurus words for "diving":
   Australian crawl, acrobatics, aerobatics, aquaplaning, aquatics,
   backstroke, balneation, banking, bathe, bathing, breaststroke,
   butterfly, chandelle, crabbing, crawl, deep-sea diving, dive,
   dog paddle, fancy diving, fin, fishtail, fishtailing, flapper,
   flipper, floating, glide, high diving, natation, nose dive,
   pearl diving, plunging, power dive, pull-up, pullout, pushdown,
   rolling, sideslip, sidestroke, skin diving, sky diving, spiral,
   stall, stunting, surfboarding, surfing, swim, swimming,
   tactical maneuvers, treading water, volplane, wading, waterskiing,
   zoom