I was also PADI Certified. My Dive Instructor informed us that PADI is recognized world-wide, whereas if you get NAUI Certified, & go diving in various, overseas, countries, you may run into problems when you attempt to get your air tanks re-filled. He said that a lot of places won't re-fill the air tanks of NAUI Certified Divers 'cause if something bad where to happen to the diver, regardless of who's fault it was, the dive shop can be held liable for any damages that happen to NAUI Certified divers. If you stay in the U.S.A. there shouldn't be any problems. Doesn't make any sense to me if they both teach the dive students the same material, & qualify the students with the same amount of qualification dives ( 5 ). IDK rob