SDI Chapter One: The Underwater Enviroment Questions and Answers | Latest Update 2024/2025

What does "SCUBA" stand for in scuba diving? ~~> It stands for self-contained underwater breathing apparatus. List the three most important scuba diving changes that occurred in the 1950s. ~~> The three most important changes were dive tables, personal dive computers (PDC), and enhanced diving equipment. Name three different devices that modern dive computers replace. ~~> Modern dive computers replace the need for dive tables, gauges, and different alarms (audible and/or visual). What sets Scuba Diving International apart from other training agencies? ~~> SDI was the first diving agency to provide entry-level instruction and incorporates the use of dive computers. How much larger and closer do objects appear underwater and why? 2 | P a g e | © copyright 2024/2025 | Grade A+ Master01 | September, 2024/2025 | Latest update ~~> Water is denser than air, objects underwater appear closer than they actually are (25 percent closer). Objects also appear one third larger than they actually are. How much faster does sound move through water than air and why? ~~> Sound moves four times faster in the water than it does on land because water is about 800 times denser than air. What is the first color to be absorbed under