After splashdown, how do I bring my crew back to the space center?

Swimming?

@Plasma01
o...

@SamTheFox
https://www.simplerockets.com/Feedback/View/ftpMFW/Recover-Option

@Plasma01
really? it will have a recover option? amazing!

The new update will have a "recover" option, so I suggest you wait until then. For now, though, you'll need a boat or aircraft to pick the crew up.