I'm impressed with the mileage - 10km per day x 6 days a week. 60km a week of swimming, that's more than I run. And they max out at 100km a week, that's almost 20km per day.
I am going to challenge myself and see if I can swim 10km per day, for 6 consecutive days, before the end of this year. Just to feel what an Olympic quality session feels like. Right now I'm at 1km per day. Watch this space.