Does the human body absorb water while swimming?

I weigh308-312 depending on the time of day. I started weighing myself before and after my daily 60-minute swim. I consistatly absorb approximately 7=10 pounds of weight in that hour. I swim about 3/4 mile in that hour period - breast, back and freestyle 30/30/30. I suspected I was absorbing a month ago when I went to my dr. appointment. I'd weighed that morning at the Y; then swam and went to my appointment to find the 12-pounds showing up on his scale. I attributed this to scale differences, the fact that I was clothed and wearing shoes. I began weighing before and after and sure enough, because of my over-sized human "sponge", I absord perportionately. I suppose someone "smaller"; leaner BMI might absorb somewhat less... a 150lb man might only pick up 2-3lbs water??? I will continue to mintor.