Plaintiff, a volunteer worker, should have been aware that she might have "sunk in and slipped" while attempting to negotiate the steep-sloped, muddy riverbank on foot, especially given the fact that defendant had fenced off the area and had refused to allow child volunteers into it. Plaintiff's contention that her injury was caused by a latent or concealed condition and that defendant thus breached its duty to take reasonable measures to neutralize that condition (see, Walter v. State of New York, 185 A.D.2d 536, 538) is without merit. Such terrain is a natural geographical phenomenon that would foreseeably have soft or uneven spots and, therefore, would not engender such duty on the part of defendant (see, Coote v. Niagara Mohawk Power Corp., 234 A.D.2d 907, 909). Where the natural condition of the terrain is plainly and obviously dangerous, a defendant landowner owes no duty to warn of or to prevent such danger (see, Tarricone v. State of New York, 175 A.D.2d 308, 309,lv denied 78 N.Y.2d 862; Rolfe v. Galt, 102 A.D.2d 983, 984 lv denied 63 N.Y.2d 604; Diven v. Village of Hastings-On-Hudson, 156 A.D.2d 538, 539).