Snorkels are currently part of service rescue swimmer's equipment. But you must understand these personel are SWIMMING to the victim, have a helicopter overhead ( or close by if they need to make an immediate evac for a critical trauma) and are superb swimmers and water survivalists that train constantly. A victim is akin to a lost hiker. There is seldom a good reason to swim. A quick review of marine accidents show more casualties than successful swims to shore. It is best to tread water or perform the "deadman float." Again, the analogy is to a lost hiker staying put and conserving energy. I served before the rescue swimer program. Helicopter rescues were amphibious ( conditions permitting) or via Stokes litter. Usually one of us would jump in if the victim needed assistance. Swimmers from Lifeboats jumped from the stern if there were multiple victims, secure the victim and await the boats or a helo. We tried snorkels. I personally found them an obstruction. The water was usually to rough or I was half seasick myself to make their use worthwhile at my skill level. I prefered to keep my head" on a swivel." remember, rescue units are often looking for a needle in a haystack ( the wreck or crash site) and you in the water are the head of that needle.