AbstractMany depth gauges are dangerously inaccurate. It is therefore interesting to know how accurately divers can estimate depth, and whether this varies with diving experience. Six novice and six experienced divers followed a rope along the shelving bottom of a quarry and estimated their depth at nine marked points. Except for novices’ estimates when shallow, both groups underestimated their depth. The degree of underestimation was significantly less for novices than for experienced divers. Both underestimation and variability increased with depth. It is suggested that novices made deeper depth estimates than the experienced group because they were more anxious.