I'm talking about things like:

most realistic physics
most aesthetically pleasing sea
most fun to play
most immersive (pun intended (I'll sea myself out))
most activities available at sea
most variety of sea going vessels

Games with impressive seas that I've played so far:

Assassin's Creed Odyssey (Triremes and heaving seas)
Just Cause 3 (Sparkling blue mediterranean seas)
Sea of Thieves (Monsters and pirates)
Sailwind (Gentle seas and actual sailing mechanics)
Silent Depth 2 Pacific (Sneaky WW2 subs)
Cold Waters (Sneaky modern subs)
Uboat (Beautiful WW2 seas, rare shooting opportunities)
Subnautica (Thalassophobia and crafting)

I've also noticed that Ships at Sea has just gone on sale. If you've played it recently was it any good?