You can take dive pictures with your existing camera provided you have an underwater camera case. There are a range of designs available, but at the least your case should be watertight, airtight, dustproof, and crush resistant. Some cases are also manufactured to resist rust, pests and chemicals such as oil, fuel, and solvents. Additional flame retardants and UV stabilizers can be added to the plastic to protect against fire and brittleness caused by extended sunlight exposure. The housing should protect the camera not only from underwater hazards, but also life on a boat at the mercy of the waves.
A pressure release purge valve utilizes an O-ring to ensure your underwater camera case achieves a perfect seal. The valve automatically engages when the case is closed and releases when the latch is opened. Accuform foam is another material used to protect your camera from adventurous abuses. This foam is a high-density vertically scored padding that holds your equipment snugly in place to prevent jostling and jarring.
Waterproof camera housings come in a wide range of sizes for both digital and 35 mm cameras. The best cases will have undergone rigorous testing in the factory including 24-hour submersion tests, drop tests up to 48 in (121.9 cm), and 400 lbs (181.5 kg) of weight stacking.
