How do I close the water app

Be sure to spin the Digital Crown with sufficient force and speed. Roll your finger rapidly over the crown.

On your Apple Watch, make sure you’re on the Watch face. Swipe up from the bottom to bring up Control Center.

To turn off Water Lock mode;

turn your Digital Crown away from you in one continuous movement until the animated water droplet fills the circle on the screen. Your Apple Watch will then start beeping multiple times. This is to allow any water in the speaker grill to escape.