If you have a weak stomach and find yourself in rough seas, this may prove immensely important: Research by Thomas A. Stoffregen of the University of Minnesota published in the journal Psychological Science suggests that looking to the horizon may in fact help stabilize your posture (and possibly your stomach).
Stoffregen and his coauthors, Anthony M. Mayo and Michael G. Wade, know how much an individual on average rocks back and forth in normal situations – roughly four centimeters every 12 to 15 seconds. They have been studying body sway for decades. In order to see how life on the sea affects these tendencies, Stoffregen tagged along with a series of U.S. Consortium research vessels to put crew to the test.
In each experiment, the crew was asked to stand on a force plate and focus on a target near or far. On land, the crew was steadier focusing on the closer target; at sea, the opposite proved to be true. Stoffregen believes that focusing on a distance point while at sea may help differentiate the two sources of movement, that of the ship and that of your body.
Mayo, A.M., Wade, M.G., & Stoffregen, T.A. (2011). Postural effects of the horizon on land and at sea. Psychological Science, 22 (1), 118-24 doi: 10.1177/0956797610392927