I've heard that we've done more exploring in space than we have in the oceans (And not gonna lie, I think I last heard that in "The Meg", that terrible shark movie that came out this year).
From deep water crevasses, to the cold depths by Antarctica there are creatures we don't know about.
Like this Headless Chicken Monster, yeah they named it that:
Did you see it's little feet in the beginning? It has like 50 little squishy feet that it can 'walk' on. Which is terrifying, not cute: