The Altitude setting automatically adjusts the decompression calculation according to the given altitude range. You can find the setting under Dive settings » Parameters » Altitude and select from three ranges:
As a result, the allowed no decompression stop limits are considerably reduced.
The atmospheric pressure is lower at high altitudes than at sea level. After traveling to a higher altitude, you will have additional nitrogen in your body, compared to the equilibrium situation at the original altitude. This 'additional' nitrogen is released gradually over time and equilibrium is restored. Suunto recommends that you acclimatize to a new altitude by waiting at least three hours before making a dive.
Before high-altitude diving, you need to adjust the altitude settings of your dive computer so that the calculations take into account the high altitude. The maximum partial pressures of nitrogen allowed by the mathematical model of the dive computer are reduced according to the lower ambient pressure.
Traveling to a higher elevation can temporarily cause a change in the equilibrium of dissolved nitrogen in the body. Suunto recommends that you acclimatize to the new altitude before diving. It is also important that you do not travel to a significantly high altitude directly after diving to minimize the risk of DCS.
SET THE CORRECT ALTITUDE SETTING! When diving at altitudes greater than 300 m (980 ft), the altitude setting must be correctly selected in order for the computer to calculate the decompression status. The dive computer is not intended for use at altitudes greater than 3000 m (9800 ft). Failure to select the correct altitude setting or diving above the maximum altitude limit will result in erroneous dive and planning data.
If you are doing repetitive dives at an altitude other than the previous dive altitude, change altitude setting to correspond to the next dive after the previous dive ended. This ensures more accurate tissue calculations.