SDI Open Water Scuba Diver Practice Exam

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Prepare for the SDI Open Water Scuba Diver Exam. Explore flashcards and multiple-choice questions that include hints and explanations. Dive into this immersive preparation experience to ensure your success!

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How long will a scuba cylinder that normally lasts one hour at the surface last at 20 meters?

40 minutes
30 minutes
20 minutes
10 minutes

The correct answer is: 20 minutes

A scuba cylinder's duration underwater is affected by depth due to changes in ambient pressure, which impacts how much air a diver uses. At 20 meters (approximately 66 feet), the pressure is about three times greater than at the surface. This increased pressure leads to an increase in the volume of air consumed while breathing, resulting in a shorter duration of air supply. If a scuba cylinder lasts one hour at the surface, it will last approximately one-third of that time at 20 meters. This change is because the diver is now inhaling compressed air; thus, the effective air consumption rate escalates. Calculating one-third of an hour gives approximately 20 minutes. Understanding this concept is crucial for divers to manage their air supply effectively and ensure safe diving practices.