What is the term used for swimming deep in to a river during the summer period for cooler waters

Closest thing I could find or think of would be Thermocline. A point in which the warmer surface water mixes with the cooler deeper water

  dante alighieri wrote the divine comedy, a description of a spititual journey. when he wrote it , he was in exile. in florence, dante's native city, there was a social strife, they had political turmoil, and some of the   florentine names included in the narrative may have been a way that dante used to criticize his fellow citizens.