halistatic
Concerning an area of a sea or ocean that has no currents passing through it, especially the area at the centre of a gyre.
Thus, by describing a great circle in the ocean, the Gulf Stream and its continuations in the North Atlantic form the boundary of an enormous eddy, which the German scientist Haeckel wished to regard as a "halistatic area." This is a term which you will not find in your dictionary or encyclopedia. It explains what Haeckel thought of the comparative changelessness of this portion of the ocean.
Where it comes from
From halo- (“sea”) + -static. For unclear reasons the original i vowel of the Ancient Greek stem was used (compare halicore).
Adapted from the Wiktionary entry halistatic (CC BY-SA 4.0).