Training and genetics.
On the flip side, out of all the genetic benefits one can get, this might be the lamest one. :(
I recently tried the 'Wim Hof' method, and was well over 4mins after just a few days practice, and I just went snorkelling and was able to outlast all those I went with. If I was healthier I am sure I could get longer still.
Like why isn't some Peruvian on Nepalese person the record holder? Lakes too cold for recreational swimming maybe?