Depth jumps are explosive jumps onto an elevated box of a given height, usually somewhere between 12"-36". This builds explosive strength in the legs and is a fundamental excercise for every plyometric routine. Sometimes a series of "depth jump boxes" of different heights are placed in a row (shortest to tallest). After explosively jumping onto the first box, jump down and IMMEDIATELY jump onto the next box. Repeat this on all boxes. Watch your shins though b/c if you miss they will bleed.