All centers are affiliated with one of the major certifying bodies, with PADI (Professional Association of Diving Instructors) being the most common.
None of the centers are certified, it is a gamvke to go. 
mnli hypothesis: None of the centers are certified, it is a gamvke to go.  premise: All centers are affiliated with one of the major certifying bodies, with PADI (Professional Association of Diving Instructors) being the most common.