Excerpts — Scuba Diving-5th Edition
Scuba divers use several hand signals that are not used for skin diving. The signals specific to scuba diving relate to air supply.
Many factors affect your plans for a dive or a diving trip. Keep the following considerations in mind when you are looking ahead to a dive outing.
There are many diver training organizations and thousands of professional diving educators. Your phone book might list diving businesses that offer sanctioned courses. Many universities, community colleges, and recreational departments also offer scuba courses.
An object’s ability to float in a liquid depends on the density of the object compared with the density of the fluid in which the object is immersed. Water exerts pressure equally in all directions, even upward. You can feel the upward force (buoyancy) of water when you try to push something under the water.