There are many different scuba diving certification agencies that are currently active in the world. Each of these agencies provide people with instruction to become a certified SCUBA diver and have similar requirements for a basic level of certification. All major agencies have non-expiring certifications that are recognized worldwide. They also all help regulate the sport and contribute to dive safety, dive medicine research, and conservation worldwide. So how does a person decide which agency to be certified through if there are multiple options? In the beginning, a person should consider cost, convenience, and reputation over certifying agency as they mostly have very similar training requirements, but as a person looks at continuing their dive education, certain agencies may be better than others for what they would like to do.
The 2 largest certifying agencies in the United States are NAUI and PADI. Each of these agencies is recognized and operates worldwide. They also both offer multiple levels of certifications in both recreational and technical diving. PADI tends to be available at most dive locations and has the most members currently. NAUI is the oldest certifying agency, is the second largest organization behind PADI and promotes dive safety through education. Check out the links below to learn more about these two agencies.
Leydens' Dive Shop is certified to issue certifications for NAUI, SEI, PDIC, and CMAS. Learn more about these wonderful organizations at their links below
Whatever agency you choose to become certified through, make sure you dive within your training and comfort level at all times and seek more training as it becomes necessary. Many agencies offer multiple certifications that can help you safely navigate new diving situations.