I'm just starting sexond trimester and still having constant nausea, wondering when it will go away. I was told and what works for me is to drink small sips of water...like half a shot glass amount every 15min. It's such a small amount it easily absorbs and doesn't fill ur stomach so ur nausea isn't worse. When I was vomiting I try to drink something with electrolytes like gatorade to replace all that I lost with the puke. It's incredible but this small amount keeps u pretty well hydrated...I guess when u add it up it turns out to be a good amount of fluids.
Hope this helps u. No advice on curing the seasickness feeling, if u find something LMK!