During altitude dives when do you need to make corrections to depth?

• A. No correction is required for any altitude
• B. Corrections are required for all dives at all altitudes
• C. Corrections are required for altitudes between 300 and 1000 ft for certain dives
• D. Corrections are required for altitudes above 1000 ft for all dives

Answer: (D)

Altitude changes the pressure at the surface, and that shifts how much total ambient pressure you experience underwater. Dive tables and computers are built around sea-level surface pressure, so when you go to higher elevations the same depth doesn’t translate to the same pressure exposure as it would at sea level. At elevations above about 1000 ft, that difference becomes large enough that every dive needs depth corrections to reflect the true pressure exposure. By using altitude-adjusted tables or a dive computer set for altitude, you ensure no-decompression limits and decompression schedules are accurate. Ignoring these corrections at high altitude can lead to incorrect planning and a real risk of decompression illness.