As the reef modules become more densely populated, it gets tighter between the discs. Which, I imagine, is what your looking for in artificial reef living. Chief among the list of amenities, is not getting eaten while taking a break.Grayton Beach Artificial Reef South Walton Artificial Reef Association SWARAWalton County Florida, USAOlympus OM-D E-M5 14-42mm II Lens PT-EP08 Underwater Housing, PPO-EP01 Lens Port