What Have Been the Biggest Moments in Swimming?

Trudy Ederle becoming the first woman to swim the English Channel and beating the men's record by more than 2 hours.

https://en.wikipedia.org/wiki/Gertrude_Ederle

Mary T's 200 fly is #2 on my list. These swims were generations ahead of their time.

Sometimes a swimmer will put up a new time that shows everyone else what is possible, but these swims were just so unbelievable that it took ages for other swimmers to even seriously challenge them.  

Addendum: Actually, the current women's 200 LCM fly record is also such a swim. It's a shame that it is widely considered suspect. 

Trudy Ederle becoming the first woman to swim the English Channel and beating the men's record by more than 2 hours.

https://en.wikipedia.org/wiki/Gertrude_Ederle

Mary T's 200 fly is #2 on my list. These swims were generations ahead of their time.

Sometimes a swimmer will put up a new time that shows everyone else what is possible, but these swims were just so unbelievable that it took ages for other swimmers to even seriously challenge them.  

Addendum: Actually, the current women's 200 LCM fly record is also such a swim. It's a shame that it is widely considered suspect.