The Collaborative International Dictionary of English v.0.48:

Sea cocoa \Sea" co"coa\ (Bot.)
   A magnificent palm (Lodoicea Sechellarum) found only in the
   Seychelles Islands. The fruit is an immense two-lobed nut. It
   was found floating in the Indian Ocean before the tree was
   known, and called sea cocoanut, and double cocoanut.
   [1913 Webster]