- Before the development of accurate dive computers, scuba enthusiasts relied on the Navy dive tables to plan safe dives. While tables are helpful, they cannot accurately account for the changing conditions of the real world. During the late 1950s, research projects attempted to use mechanical devices and analog computers to simulate the effect of outgassing on bodily tissues. But these experiments produced mixed results. Advances in computer technology and miniaturization made the practical dive computer possible by the 1980s.
- A modern dive computer will display the current depth as well the maximum depth reached on the dive. Combined with this information will be a display of how much time the diver can remain at the current depth without making a safety stop as well as the total time of the dive. Some dive computers will provide additional information such as water temperature or will give alerts if a diver is ascending to the surface too quickly.
- A diver experiences increasing pressure the deeper he goes underwater. Under increased pressure, normally inert nitrogen will dissolve in the diver's bloodstream. Once this happens, the diver's blood and tissues are a little like a shaken can of soda. If the pressure is released too quickly, the dissolved nitrogen bubbles out of solution. In severe cases of decompression syndrome, these bubbles can cause brain damage, strokes and even death. A good dive computer helps a scuba enthusiast dive responsibly and safely.
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The Navy dive tables are based on several assumptions that might not accurately reflect the real-world conditions recreational divers experience. The Navy dive tables assume divers will descend at a constant rate to a given depth and remain at that depth for a given time before surfacing at a constant rate. The Navy tables also assume divers will strictly follow a dive plan. In the real world, recreational divers ascend and descend constantly, and often deviate from established dive plans. The development of the dive computer allows recreational scuba divers to account for these differences to avoid decompression effects.
- Although helpful safety tools, dive computers are no guarantee against the bends. Operating a dive computer at or beyond its design limitations, ignoring a dive computer's suggestions to slow or stop ascent to the surface and similar misuse might leave a diver at risk for decompression syndrome. Dive computer accuracy is also limited by the significant physiological differences between divers. Age, weight and overall health play a contributing role in decompression syndrome, and are largely not taken into consideration by dive computers.
