>>285481412
That's probably more like actual seasickness from the moving water, 
OR
an unoptimized game with a low frame-rate. 
Bad frame-rates/latency will jack you up. Also if there's a lag between your hands and actions. Some games use differed rendering and don't hit the frames, and therefore feel "floaty". 
UE4 is differed by default. 
Oculus says that MSAA is very important, but at this point I completely disagree.