Apple watch stuck in water lock mode

Keep rotating the Digital Crown (the round button), causing the coloured circle to grow larger, until your Apple Watch unlocks.

If the Digital Crown does not work as expected, it may help to clean it by following the instructions here:

Use the Digital Crown on your Apple Watch - Apple Support

You can try force restarting the watch or closing the forefront overlay,

Hold down the power button then release when you get all of your options and then hold the crown down until the screen changes, see if this helps.

If not force restart the watch (think also clears cache) hold down both the power button and crown continuously until the screen goes black and you see the apple loo, could b upwards of 10/15 seconds.

Hope this helps.