Minimum audible angles (MAA) of a harbor seal were determined using a click-train stimulus (left-right, forced choice) and found to be 9°±4° underwater and 3°±4° in air. After accounting for the sound-speed differences, the MAAs and the similarities of the psychometric functions suggest that interaural time differences provide the most important clue. The findings indicate that the interaural distance is the same in both media. An implication of this is that nonbony tissues are not sound transparent in water. MAAs in air were determined using other signal types. Click trains and 1/3-octave noise sources above 3 kHz were localized with greater acuity than sinusoidal or low-frequency noise stimuli. The findings indicate that signals containing well-defined time clues are localized more readily than signals containing only intensity and/or phase information.