Even if you’ve never succumbed to seasickness yourself, you know
that the associated weakness, sweating and especially the nausea can ruin a day
of diving. If you have experienced seasickness, you know the effects are not
fatal, although you may have wished they were at the time.
What causes seasickness? Even though the mal de mer seems to center in the
stomach, it’s actually a form of motion sickness. It’s caused by the movement of
fluid in the inner ear labyrinth, an organ that helps maintain your equilibrium.
Some people seem more susceptible to seasickness than others. However, even
those who swear they don’t get seasick may still find themselves affected in
certain situations. The rocking motion of a boat doesn’t have to be severe, as
in rough seas, to disrupt the inner ear. And the potential for seasickness is
increased by dehydration, alcohol use, a case of nerves or diesel fumes from the
boat’s engine.
Reduce the chances of becoming seasick when boat diving by avoiding the stern
(back end) where diesel fumes linger. Likewise, don’t linger below deck or in an
enclosed space (the head in particular). Also, the higher you are on a boat, the
greater the rocking effect.
Instead, remain outside on the main deck, near the midline of the vessel, where
movement is least. Fix your eyes on the horizon to give your brain a stable
reference point.
If all your precautions fail and you feel like you’re going to become ill, DON’T
head for the head! Instead, grab a clear spot at the rail and let nature take
its course-this purging usually makes you feel a lot better. Be sure to choose
the leeward rail, where the breeze is blowing away from the boat. Then rest and
sip water to rehydrate.
Mild seasickness is sometimes cured by diving because it gets you away from the
boat’s motion, but underwater is definitely not the place to throw up.
There are several forms of seasickness preventatives on the market that may work
for you.
…excerpt from Dive Training, March 2004.