pelagic
Living in the open sea rather than in coastal or inland waters.
Besides, seeing a shark in an aquarium tank is not the same as seeing a shark in the wild, in its natural, pelagic habitat.
Of or pertaining to oceans.
Drifting idly around a broad oceanic arc, the bottle collides softly with tens of thousands of pelagic plastics all colonized by hard-shelled organisms, including barnacles, coralline algae, foraminifera and bivalve molluscs.
Where it comes from
From Latin pelagicus (and possibly pelagus); from Ancient Greek πελαγικός (pelagikós), from πέλαγος (pélagos, “sea”). By surface analysis, -pelag + -ic.
Adapted from the Wiktionary entry pelagic (CC BY-SA 4.0).