Cpl. Manuel Concreras, a wireman with 2nd Battalion, 3rd Marine Regiment, holds Cpl. Jared Malczewski's legs as he prepares to orient himself upside down in the base pool as a part of Shallow Water Egress Training June 3, 2015 at the base pool aboard marine Corps Base Hawaii. In this scenario, the Marines learned how to don their oxygen apparatus while underwater. - Cpl. Manuel Concreras, a wireman with 2nd Battalion, 3rd Marine Regiment, holds Cpl. Jared Malczewski's legs as he prepares to orient himself upside down in the base pool as a part of Shallow Water Egress Training June 3, 2015 at the base pool aboard marine Corps Base Hawaii. In this scenario, the Marines learned how to don their oxygen apparatus while underwater.