Karoo's USB port was specifically designed to not require the use of a rubber plug to protect it, even in wet conditions. Here, we deliberately flood the port and plug in a live charge cable, and you can see that the device begins charging without issue. The port can also be gently rinsed clean of mud and grime.
In the Settings app, under "Strava," you can opt for your Karoo to automatically upload your ride to Strava. If you want, instead, to manually upload rides to Strava later, here's how you can do it.