You can leave your camcorder on "auto" and hope for the best. This lets the camcorder make up its own mind about what settings will work best to achieve the best looking video. But often, auto isn't enough. If you own an underwater camcorder, or have a housing for your traditional camcorder, here are some tips to get the most of your underwater experience:
Tip #1 - Boost the Exposure: Exposure control is one of the most common features on a camcorder: it regulates how bright or dark your video appears. When you're filming underwater, it's inevitably going to be darker, so increasing the brightness through exposure control can compensate.
Tip #2 - Use an Underwater Mode: If you're filming with an underwater camcorder, chances are it has an underwater mode. This mode will optimize the camcorder's settings for underwater shooting. Before you start using it though, you should try to take some sample footage first. Sometimes the results are not as good as what you'd find in "auto" mode.
Tip #3 - Boost the Display Brightness: If you're scuba diving, or just swimming around the pool with your goggles on, it's going to be difficult to see what you're doing. Adjusting the brightness of the camcorder's LCD display will help you properly frame your video. Many, though not all, camcorders allow you to bump up the display brightness in the menu settings.
Tip #4 - White Balance: Some camcorders will let you manually set white balance to adjust the camcorder to a new lighting environment (check your owner's manual to see if your particular model supports manual white balance adjustment). If have this option, you can typically aim the camcorder at a subject while it analyzes the new lighting conditions and adjusts accordingly. If you're using an underwater housing and not a waterproof camcorder, you likely won't be able to access the menu to perform a manual white balance.
Tip #5 - Easy on the Zoom: With waves rolling overhead, the light beneath the water is going to be constantly changing. That's going to make it challenging for your camcorder to focus quickly. If you're constantly zooming, you may experience some focusing delay, so it's best to use the zoom sparingly. If you need a close up, move yourself, not the lens. [Note: this does not apply when filming underwater animals with sharp teeth.]
Tip #6 - Keep Image Stabilization On: Image stabilization keeps camcorder footage steady, if you're not. Many optical and digital image stabilization systems in a camcorder can be turned on or off. If you're heading underwater, be sure to turn on your camcorder's image stabilization (usually done through the menu). You're going to be moving a lot underwater, and it will help steady your footage.
Tip #7 - Experiment: There's no "golden rule" when it comes to underwater filming. You'll have to play around with your camcorder's features to get the best settings possible. That being the case, it pays to familiarize yourself with your camcorder's features before you dive in. The best way to do that is by reading the manual. Yes, I know this is like being told to eat your spinach. But sometimes with camcorders, as with life, there are no shortcuts.