Heaving waves out on the treacherous ocean are complemented by complex, layered shallows on island beaches.
Individually lit raindrops, rippling and bubbling puddles, and sophisticated water reflections augment stormy weather for landlubbers.
There's also a new swathe of technical wizardry that underlies Captain Edward Kenway's boat-hopping antics as Caribbean warships collide and boarding commences.
And more plants on screen don't just look better but make for better stealth gameplay, with pirate king Kenway sneaking about in long grasses and under the cover of wide-leaved vegetation before making that inevitable pounce upon patrolling guards.
While most publishers are busy pushing their titles on Xbox 360 and PlayStation 3, Ubisoft has decided to let us see what the Xbox One and PS4 might be capable of, "Assassin's Creed" style.
But with the game part of official upgrade programs rolled out for Xbox 360 and PlayStation 4 players, there's less at stake for Ubisoft when talking up next-gen capabilities.
"Assassin's Creed IV: Black Flag" releases on Xbox 360, PlayStation 3 and Wii U the week of October 29 (November 28 in Japan), and on Xbox One and PlayStation 4 at the new consoles' launch in mid- to late-November; a Windows PC release is confirmed for this year but as yet undated.