I've never spent 4 whole days on the sea before this last dive trip. I can't say I really got my sea-legs, though I puked but once - and that was mostly because the water was rough on the surface. The thing about diving is you don't get seasick underwater, where everything - sound, light, and movement - is muffled and muted, but you do get seasick once you finish the dive. At least I did.
There was plenty of time in between dives to chill out and stare at the sea. When it was calm, you could almost think it was Homer's "wine-dark sea".