Abstract: Employee #1, a SCUBA instructor, and her student drowned during an instructional dive to a depth of more than 60 feet in water that was below 45 degrees. Both divers started with full tanks; however, after the accident, the student's tank was 3/4 full and the instructor's tank was empty. It is likely that the regulators failed due to icing. It is against the regulator manufacturer's instructions as well as against PADI instructions either to dive to a depth of more than 60 feet in water colder than 45 degrees, or to dive in water colder than 45 degrees without a regulator modification to reduce icing potential. The employer also failed to provide either an independent breathing air supply for each diver (29 CFR 1910.424(c)(4)) or an air supply independent of the breathing air for inflating the buoyancy control device (29 CFR 1910.424(d)(4)). The PADI manual for deep dives over 60 feet also requires an emergency breathing air supply tethered at 15 feet, which the employer did not provide. 1910.132(a) and Section 5(a)1 were cited.