[jessaustin]

There is wide variety in human resistance to cold, including cold water. It isn't surprising that someone who had lived in Russia could spend a great deal of time in the tropical ocean. Some people who live in the tropics can do that!

Incidentally, this variation seems not to be genetic, or maybe it is epigenetic. When visiting India during the "winter" with a friend who was born there but had lived in USA for decades, his family was shocked at how both of us were comfortable in short sleeves while they shivered in heavy coats.