Water resistant digital cameras, broadly designated, are digital cameras designed to withstand anything from low levels of water exposure, like spills and rain spray, to complete immersion. They can include design features ranging from partially sealed electronics to solid, impermeable plastic casings. It is important to note that cameras marked as 'water resistant' are not the same, and will not protect against moisture as well as cameras that are waterproof, and advertised as fully immersible. Water resistant digital cameras are rated along this spectrum by the Japanese Industry Standard (JIS).
The JIS grades of water resistance run from zero to eight, and cameras are rated following a battery of tests. Grade 0 cameras are completely non-resistant to water. Grade 1 cameras are resistant only to water drops that fall vertically, like rain. Grade 2 cameras are protected against vertical water drops when the camera is slightly tilted.
At higher levels on this scale cameras become more waterproof. Those at Grade 3 are resistant to spraying water and rain, while Grade 4 cameras are protected against splashing water. At Grade 5 cameras are resistant to water projected from jets. Grade 6 cameras are protected against more powerful water jets, and may be considered 'watertight.' Immersion resistance begins at Grade 7, at which cameras are protected against temporary submersion, and finally Grade 8 water resistant digital cameras are protected against the effects of being continuously immersed in water.
Water resistant digital cameras with a Grade 8 rating may be used while submersed in water down to a certain depth, which is usually specified by the manufacturer. These devices are generally considered true underwater cameras, and are intended for snorkeling and scuba excursions. For the most part, cameras designed, and marketed as, water resistant tend to sacrifice more advanced features found on similarly-priced conventional cameras, such as strong zoom lenses, high definition recording, and large liquid crystal display (LCD) screens.
Nearly all water resistant digital cameras feature internal zooms. These allow for modest zooming, without the lens extending out beyond the body of the camera. An approximate rule of thumb is that, for the same price, the features on a water resistant digital camera lag two years behind those available on a conventional digital camera.
An alternative to standalone water resistant digital cameras exists in the form of watertight housings, which allow virtually any camera to be used underwater. Such enclosures are bulky plastic casings that literally house a normal digital camera, and have a glass port through which the lens can take clear pictures. Depending on the model, these can allow for use at snorkel and scuba-diving depths, and present a reasonable option for taking underwater photos.