How to go back to main screen after my swim activity?

Had my first swim this morning.  After my activity, i press stop and save. Then the it shows me my summary and interval if I press down. Issue is : I can't go back to main screen/watch face !   The back button doesn't allow me to go back.  So i did a power off and on.  Is it suppose to be like that? Or do  I have to press start and delete the history?