chartered, hired, leased

uncharted, unexplored, terra incognita, untrodden, unmapped, unfamiliar, untraveled, unnavigable, murkiest, perilous, untested, daunting, tricky, illimitable, pathless, inaccessible, dicey, untethered, trammeled, untapped, unimagined, treacherous, unsurveyed, rocky, untamed, undiscovered, inhospitable, rarefied, unfathomed, twilight zone, untried, adventurous, unpropitious, unexploited, unclimbable, esoteric, propitious, obscure, challenging, unknown, ungoverned, expansive, labyrinthian, unstudied, uncertain, abyssal, headlong, vaster, fertile, unsettled, problematical, turbulent, unplumbed, unreachable, explorable, chthonic, unforgiving, unregulated, desolate, circum, lawless, undreamed, unthought, intuitional, subaquatic, unformed, estuarial, limitless, bumpy, subpolar, barren, untraditional, depthless, deeper, labyrinthine, inscrutable, abstruse, rarified, deltaic, uncommercial, roiling, vasty, biogeographical, moonlike, undefined, risky, liminal, unstable, unacquainted, subterranean, surmountable, tabula rasa, unpromising, twilit, steep, circumscribed, thorny, constricted, nebulous, fathomless, navigable, difficult, trackless, charted, hilly, untravelled, semiautonomous, strewn, waterless, conquered, swept, uninhabited, unpeopled, unpopulated, untracked