While the snorkeling tours in Akumal Bay continue to be halted by PROFEPA, the newest info suggests that individual snorkelers are being strongly discouraged from wearing fins as well.  This is being done in order to help prevent snorkelers from standing on the coral (which kills the coral over time) as they adjust their masks, etc.  For the least amount of disruption to your snorkeling experience, be prepared to snorkel in front of the Secrets resort instead of further north, and please respect the buoys/markers for now.