[rrobukef]

Imagine how fast Phelps could swim with this!

[matt_heimer]

Given that he optimized his training for swimming and not cycling I think he might do better with fins. His top speed of 7.2 - 9.6 km/h is freestyling without fins. He reached somewhere around 13 km/h using a Lunocet monofin.

[space_oddity]

I'd watch this