Disposable underwater cameras don't get the benefit of the doubt when it comes to taking decent photographs on your underwater safari.  If you say the word disposable then people will automatically think "minimum quality" or "last resort".  The fact of the matter is that these cameras take pretty decent pictures depending on the situation.  If you are just at the beach and near the water you will think twice before exposing you "dry land" digital camera to these elements because you fear damage.  Damage such as sand, water, sun to be specific.  This is where you disposable underwater camera will shine.

Chances are that you are taking casual photographs and not going for the Pulitzer prize in photography.  The disposable will do more than an adequate job in recording your day at the beach.  The other situation where the disposable underwater camera holds its own is in shallow depth underwater photography.  At depths of 30 feet or less it will take good pictures as long as you stay within the rating for the camera.

The other key area that you should be aware of when using these cameras is the time of day.  If you are using it in the morning or late afternoon you have to take in consideration the angle of the sun on the water.  During this time of day the angle will be shallow and less able to penetrate the water.  This means taking pictures will be less successful because of less light.  It's best to shoot these pictures at midday when the angle of the sun is steepest.  Also take note of the clarity of the water.  You want to shoot when the water is relatively clear with little sediment.

When using a disposable underwater camera also keep in mind that water causes the image to distort.  You will have to keep the image close in order to take an acceptable shot.  Lastly, try to find a camera that has a sturdy strap and one that is tight enough that it won't come off in the water.  It is very easy to lose your camera underwater, and depending on the circumstance can be quite difficult to retrieve.  You'll also want the strap on the same side as the photo button for ergonomic reasons.