If you are using your phone primarily for its workout app, see if you can set up the app before getting on the water in a manner that requires little or no intervention during your paddle.
Make sure the screen will not go blank (power saving mode?) during workout
If the app has a lock that prevents random brushes/pressure input interaction - definitely engage that lock mode.
Emergency Beacon IOS only, at touch of a button will send GPS coordinates to pre-programmed destinations, text, email
SafeTrx android and ios app that allows on water group members and on land friends to track group members. More extensive support is available for Search and Rescue services with licenses. But the standalone app works for the group tracking between personal phones carried by users on the water.