Somewhat unpleasant, it affects some people more than others. With concerns, as I was always the one in the SaturdaySki Bus who usually succumbed, I found out a few things. 

The nervous system when receiving conflicting inputs from eyes, inner ears and other sensors triggers a reaction one and the same, believing that the body has injested poison.  God bless it.  

The body has adaptive powers, thankfully and the queasiness eventually dissipates or so they encourage. In my case, and this is considered par for the course, about 48 hours.  I tried using a Prescription Scopolamine transdermal patch behind the ear which seemed to help somewhat but the honest cure is to endure.  The body becomes used to and adjusts to the motion. On day 3 offshore, I had my sea legs finally. In fact I could perform normal task like reading or galley work without concern. 

At one point I faced an advanced real test: Our boat, assuming a significant angle of lean while on port tack spilled the contents (gravity rules) of a bookcase shelf on the high side clear across the saloon to the other. That would be our beer bottle(s) meant for celebration at journeys end… (Don’t Drink WHILE Boating) and some of them were smashed during the crashing transfer. It was middle of the night, cabin lights dim, and imperative that the broken shards be disposed of. The space reeking like a frat house on a Friday Night, was hot and humid and still halfway on its ear – –  motion on. Since I had improperly stowed the goods I took to the mop up and survived the ordeal. It was after task that I realized that I hadn’t been phased. 

So there’s hope for those of us who don’t automatically take to seafaring. BTW, when Calling to Neptune over the side. Direct things well away or at least be ready with a wash sown bucket follow up. The contents of ones stomach reacts with the [fiberglass] gel coat and it’s a bitch to buff out after the fact!