Another treatment is an acupressure wrist band. It applies pressure to a particular point on your wrist which can prevent the feeling of nausea. Here's an interesting treatment that was found. It is a treatment that works on some after they are feeling queasy, rather than as a preventative. Immerse your feet in ice water.
Anecdotal reports indicate it helps some people.
There are other preventatives, such as over the counter and prescription medications. Most should be taken in advance of diving and not on an empty stomach. Be sure to read the instructions. Dramamine is one that has been used for years. Meclizine and bonine are also effective.