I've had really good experiences with Scopace, the pill form of the scopolamine patch. I'm pretty susceptible to motion sickness, can't do anything in a car besides look out a window. A couple of years ago we took a boat tour out of Seward, AK. It was supposed to go to Kenai Fjords but due to rough seas, we got a tour of resurrection bay instead. The tour started out with a quite good prime rib & salmon buffet. About halfway through, we had to cross the bay, where it meets the gulf of Alaska. At least half of the passengers lost their lunch. I was fine because I took scopace before we departed. I can now also do 'heads-down' tasks in a moving car, like read a book or play with a smart phone.

I first read about scopace in a flyertalk trip report. I'm pretty happy to have found a 'cure' that works for me.