Certified Hyperbaric Technologist Practice Test

True or False: Divers must use special diving tables when diving in lakes at altitudes greater than 2,000 feet.

1. True

2. False

3. Only for night dives

4. Only for deep dives

The correct answer is: True

Using special diving tables for dives conducted in freshwater bodies at higher altitudes, such as lakes located above 2,000 feet, is essential due to the effects of atmospheric pressure on gas absorption by the body. At higher altitudes, the atmospheric pressure is lower than at sea level, which affects the behavior of gases during dives, specifically concerning nitrogen absorption and elimination. Standard diving tables, designed for sea-level conditions, may not accurately reflect the decompression and safety limits for divers operating in these changed pressure environments. Therefore, divers must refer to altitude-specific diving tables that account for these conditions to prevent decompression sickness, also known as "the bends." These specialized tables provide the necessary adjustments to ensure the divers' safety and proper ascent rates to avoid complications. In the context of the options provided, this is why the statement is true. There are no specific exceptions noted in the form of night or deep dives that would negate the need for altitude considerations in the use of diving tables.