The Collaborative International Dictionary of English v.0.48:

Water hare \Wa"ter hare\ (Zool.)
   A small American hare or rabbit (Lepus aquaticus) found on
   or near the southern coasts of the United States; -- called
   also water rabbit, and swamp hare.
   [1913 Webster]

WordNet (r) 3.0 (2006):

swamp hare
    n 1: a wood rabbit of southeastern United States swamps and
         lowlands [syn: swamp rabbit, canecutter, swamp hare,
         Sylvilagus aquaticus]