An attempt was made to evaluate the performance of SCUBA divers in pulling the detonator knob on the diver's personal flotation device while treading water. Three shapes, three sizes, and three positions of the detonator knob were tested to determine their effects on the time it took divers to activate the emergency detonator. Three different glove conditions were also tested (bare hands, cotton gloves, and three-fingered mitts). The size, position, and glove type made a statistically significant difference in the time it took the diver to activate the detonator on the diver's personal flotation device, while the different shapes of the detonator knob did not show any significance. The results indicate that detonator knobs should be at least 51 mm in diameter and located on the middle portion of the vest.