A technique for locating a point source in a constant velocity medium using time delay measurements from a passive stationary sensor array is applied to the localization of underwater biological transient sources. The curvature of the spherical wave front emanating from a source is sensed at a three-element linear receiving array by estimating the inter-sensor time delays, which are then processed to extract the range and bearing of the source. The technique is used to estimate the source positions of snapping shrimp sounds recorded in Sydney Harbour (Australia) during a high-frequency sonar experiment. Plotting the source positions for a series of acoustic transient events produces a spatial distribution of the local snapping shrimp population. Passive ranging errors caused by imperfect knowledge (noncollinearity) of the sensor positions are discussed. In addition, an acoustic method is presented for estimating the in situ sensor positions of the array by processing the sensor data for mechanical transients produced by spatially distributed sources with known positions.