Air Force pararescue trainees participate in the water confidence introductory course at Lackland Air Force Base, Texas. During the course, trainees learn mask and snorkel recovery, buddy breathing and other techniques. Pararescue introductory training includes physiological training, the obstacle course, marches, dive physics, dive tables, metric manipulations, medical terminology, cardiopulmonary resuscitation, weapons qualifications, history and leadership reaction. (U.S. Air Force photo/Staff Sgt. Jonathan Snyder)