Jamieson, Fausset and Brown on 1 Samuel 23:29

29. David went up from thence, and dwelt in strong holds at En-gedi--that is, "the spring of the wild goats or gazelles"--a name given to it from the vast number of ibexes or Syrian chamois which inhabit these cliffs on the western shore of the Dead Sea (Jos 15:62). It is now called Ain Jiddy. On all sides the country is full of caverns, which might then serve as lurking places for David and his men, as they do for outlaws at the present day [Robinson].