I think that being an experienced swimmer brings some bonus skills with it that support diving.
Maybe one is really fluent airway control. In choppy conditions, if an experienced swimmer gets slapped in the face with a wave, even on an inhale, they can often just automatically pause their inhale for a fraction of a second, and they don't choke. That comes from doing hundreds of cycles of swimming strokes with breath control, sometimes with waves or splashing. Weak swimmers have to really concentrate on managing the chop, and if they get slapped with a wave, they are more likely to choke.
Water related fitness is another. A swimming coach pointed out to me a couple of years ago that fitness for swimming and other aquatic activities is different from fitness for land-based activities, in that it builds stamina for breathing control and repeatedly inhaling against water pressure. One thing that makes swimming so fatiguing for inexperienced swimmers is inexperience with breath control and repeatedly inhaling against water pressure. I noticed the effect of this in rescue class, where the experienced swimmers were operating with some spare gas in the tank, while the weak swimmers were working to the limits of their fitness.
Just some anecodotal observations.
Maybe one is really fluent airway control. In choppy conditions, if an experienced swimmer gets slapped in the face with a wave, even on an inhale, they can often just automatically pause their inhale for a fraction of a second, and they don't choke. That comes from doing hundreds of cycles of swimming strokes with breath control, sometimes with waves or splashing. Weak swimmers have to really concentrate on managing the chop, and if they get slapped with a wave, they are more likely to choke.
Water related fitness is another. A swimming coach pointed out to me a couple of years ago that fitness for swimming and other aquatic activities is different from fitness for land-based activities, in that it builds stamina for breathing control and repeatedly inhaling against water pressure. One thing that makes swimming so fatiguing for inexperienced swimmers is inexperience with breath control and repeatedly inhaling against water pressure. I noticed the effect of this in rescue class, where the experienced swimmers were operating with some spare gas in the tank, while the weak swimmers were working to the limits of their fitness.
Just some anecodotal observations.