The Collaborative International Dictionary of English v.0.48:

beachcomber \beachcomber\ [Written also beach-comber or beach
   comber.] (Naut.)
   1. A vagrant seaman, usually of low character, who loiters
      about seaports, particularly on the shores and islands of
      the Pacific Ocean.
      [Webster 1913 Suppl.]

            I was fortunate enough, however, to forgather with a
            Scotchman who was a beach-comber.     --F. T.
                                                  Bullen.
      [Webster 1913 Suppl.]

   2. a vagrant living on a beach.
      [WordNet 1.5]

   3. a person who searches along a beach for objects of value,
      such as lost objects or seashells.
      [PJC]

WordNet (r) 3.0 (2006):

beachcomber
    n 1: a vagrant living on a beach