25-5. Safety swimmers have the following obligations: TC 21-21 (U.S. Marine Corps combat water survival-1 or higher, U.S. Navy second class swimmer, qualified SEAL, SWCC, EOD, U.S. Navy diver, or lifeguard-certified). All safety swimmers have completed wet silk training in the past six months (12 months for U.S. Navy personnel). All safety swimmers have been trained on activation procedures for the life preserver in their use to include manual inflation procedures.Note. The Airborne commander or air shop briefs jumpers, aircrew, JM, and WDZ control party regarding WDZ operations.WARNINGThe MC-6 should be used, if available. Care must be taken, when using the MC-6 as the porosity of the canopy is extremely limited and may create a suffocation hazard if the jumper is trapped under the canopy.