NORTHERN CALIFORNIA (Oct. 11, 2021) U.S. Navy divers assigned to Naval Special Warfare Logistics Support Unit (LOGSU) 1 assist each other with their Mark-25 underwater breathing apparatus before a high-altitude dive. The exercise is designed to qualify and maintain Naval Special Warfare personnel's altitude diving proficiency and provide opportunities for instructor qualification. (U.S. Navy photo by Mass Communication Specialist 2nd Class Alex Perlman)