WordNet (r) 3.0 (2006):

sea lane
    n 1: a lane at sea that is a regularly used route for vessels
         [syn: seaway, sea lane, ship route, trade route]

Moby Thesaurus II by Grady Ward, 1.0:

29 Moby Thesaurus words for "sea lane":
   air lane, approaches, beat, channel, circuit, course, fairway,
   flight path, itinerary, line, orbit, path, primrose path, road,
   round, route, run, seaway, ship route, shortcut, steamer track,
   tour, track, trade route, traject, trajectory, trajet, walk,
   waterway