100%. For me the greatest human physical achievement of all time is the female American swimmer who did, I think, four back to back crossings of the channel, swimming for days, through the night etc. I'm not even sure if she even exited the water at either end during the attempt. Swollen...
Very tough gig at 70. 2.5 times as many people have climbed Everest than have successfully swam the channel, and 21 miles often turns into nearer 30 with the tides. Respect.