Your camera and beach things should be very safe just left at your chairs/umbrella. Or if you feel the need to have them watched, take turns in and out of the water with your family/spouse.
There are showers on the main pathway but I don't recall any lockers. Remember the ship is just a short tramride away so you coukld also get your video/pictures, then have the family watch the chairs and shuttle the equipment back to the ship.
When we were at CC we just brought an underwater disposable with us.
(The Video camera had a problem adjusting to the humidity and would not work)