Disposable cameras are essentially packaged film cameras that can only use one roll of film. When you purchase a disposable camera, the operation is quite simple. You take a picture, wind the film and take more pictures. When all of the pictures have completed, you take the camera to photo processing center and never see it again, only the pictures that you took.
When you open up a disposable camera, you can actually see how it functions and actually get some things from it. A roll of film is inserted into the right side of the camera. All of the film is spooled out around a plastic cylinder on the right side of the camera. When you take a picture, the film is spooled back into the camera, creating a reverse process of actual film cameras and eliminating the rewind process all together.
When the disposable film camera is brought to a photo processing center, a photo tech carefully takes apart the camera in order to process the film. First, a flat screwdriver is inserted into a marked tab on the side of the camera. A plastic piece is snapped off and the inside of the camera is opened so that the film can be removed.
Also, inside of the camera is an AA battery that can be removed. If you choose, you can remove the film yourself at home and keep the AA battery as a backup. Otherwise, all of the camera components and parts are shipped to a recycling center at Kodak or Fujifilm.
Underwater disposable cameras use the same process except they are wrapped in a tight rubber lined casing that takes extra strength to break open. Some film canisters feed all of the film in and do not leave the little tab at the end. In this case, a special film tool is used to retrieve the film in order for it to be processed.