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.
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            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.
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               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.
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