Pelagic

pelagic \pə-ˈla-jik\ adjective: of, relating to, or living or occurring in the open sea; oceanic {pelagic sediment} {pelagic birds}

Etymology: Latin pelagicus, from Greek pelagikos, from pelagos sea

It’s easy to see the relationship between today’s pelagic and yesterday’s littoral, but don’t forget about January 15th’s fluvial; check it out here.