Source : Webster's Revised Unabridged Dictionary (1913)

Coastwise \Coast"wise`\ (-w[imac]z`), Coastways \Coast"ways`\,
   adv.
   By way of, or along, the coast.

Source : WordNet®

coastwise
     adj : along or following a coast; "coastal shipping"; "coastwise
           winds contributed to the storm"
     adv : by way of, or along the coast; "we were travelling
           coastwise"