In my opionion, forget about the sea sickness pills, patches, wrist banks, etc. available in the states. Common sea sickness pills available in the states make many SOOO tired. For me personally they make me feel downright lousy. However, in Mexico they have a sea sickness pill that is available there, in Canada I believe and throughout Europe but, of course, the USDA has not approved it so you can't buy it in the states. You However, in Cozumel you can buy it at the larger pharmacies on the back streets (not the ones on the front streets that push Viaraga all day). It is called Cinnarizine. IF you google it you will see it has been cited as one of the most used drugs for seasickness within the British Royal Navy. The owner of our prior dive op recommended it when my wife got sea sick. Furthermore, unlike other sea sickness pills, this one DOES NOT MAKE YOU TIRED and you can even take it IF YOU START FEELING SICK and it will usually reverse symptoms. I would definately recommend it for your wife over anything available in the states. Take it daily before heading out as a precautionary measure.
---------- Post added February 1st, 2015 at 02:00 PM ----------
From Wikipedia: "Additionally, cinnarizine can be used in
scuba divers without an increased risk of
central nervous system oxygen toxicity which can result in seizures, and is a high risk in closed-circuit oxygen diving.
[32] This is also relevant to divers who could potentially have to undergo hypobaric decompression therapy, which uses high oxygen pressure and could also be affected by any cinnarizine-induced CNS oxygen toxicity risk. However, cinnarizine does not heighten toxicity risk, and in fact, evidence even seems to suggest that cinnarizine may be beneficial in helping delay O2 toxicity in the central nervous system.
[32] There is also evidence that cinnarizine may be used as an effective anti-asthma medication when taken regularly.
[33]"