Very nicely done, technically. And the marketing message is both true and useful: Swimming at sea is surprisingly hard, and life jackets make a huge difference.<p>I was once a very strong swimmer, and back then, I tried swimming 60 feet to shore in water with choppy, 6-inch waves. I wound up repeatedly inhaling water and choking. To combat this, I tried to keep my head high above the water, which was exhausting. After 30 feet, it was clear I was in real trouble, so I called to the rowboat shadowing me 5 feet away and they towed me to shore.<p>Similarly, cold water will shut me down frighteningly fast—even with a wetsuit and lifejacket, I've been stunned into near immobility after less than a minute of swimming. And I'm somebody who grew up swimming in the Gulf of Maine, which can be frigid (because Cape Cod deflects the warmer Gulf Stream eastward). The actual risk here is cold shock, not hypothermia—rapid vasoconstriction in your limbs will flood your core with blood, causing your heart to work much harder to maintain circulation. It's incredibly draining.<p>A life-jacket will keep your head above water with minimal exertion. This means that (a) you keep breathing and (b) you remain visible to rescuers. It turns survival from an incredibly strenuous and terrifying athletic event into largely passive floating.