NAUI - National Association of Underwater Instructors
NAUI Worldwide is the world's most respected, largest non-profit diver training organization in the world. Established in 1959 as a membership association and organized solely to support and promote Dive Safety Through Education, NAUI continues as the recognized leader in innovative education. NAUI Worldwide members offer a full range of training programs from Skin Diver through Instructor Course Director, with dozens of specialty courses including Nitrox and technical diving. Thousands of member instructors, dive businesses, resorts, and service centers are located in countries throughout the world.
https://www.naui.org/