Oh do they?  Water is slightly more dense than the human body, thus water supports the swimmer's body's weight.
Since the human body is only slightly less dense than water, water supports the weight of the body during swimming
I like to swim even when I'm not very good at it. Oh nice!  I know people swim for recreation, exercise, sport or even survival!  Some swim in salt water, some in fresh water. Yes there are some amazing pro swimmers like Micheal Phelps, do you remember how many gold medals has he won? Oh Michael Phelps is retired from competitive swimming now, but he won 28 medals.  I don't know how many of those were gold. He was the most successful Olympian ever! Wow, amazing!.  Are you any good at swimming or other sports? Well since I'm a bot I don't swim or do sports.  But did you know that in some countries, it's compulsory to take swimming lessons?  It's part of the school curriculum! Cool!  Do you know about any specific benefits of swimming? Well one benefit is that compared to running, swimming is "low-impact." That is true, it is some times used by runners and other athletes while recovering from injuries.
Since the human body is only slightly less dense than water, water supports the weight of the body during swimming.