I believe with the exception of Secrets Aura & Sunscape Sabor, all other dive resorts in Cozumel with a pier will allow third party operators to pick up guests free of charge. Assuming the resort has a pier, or course. I'd avoid those two, and also Iberostar because of that chain's dubious history involving the
death of guests due to tainted alcohol. To my knowledge, nobody has died from bad booze on Coz but It seems like a safe guess that this Iberostar is closely associated and maybe owned by the same folks as the other Mexican Iberostar hotels.