Carcharhinus amblyrhynchos. A gray reef shark passes above. Gray reefs are common sights in the Marshalls. At the southern end of Kwajalein Atoll, where there is considerable diving activity, the gray reefs are not as prevalent as they were 20 or 30 years ago. Either they are accustomed to divers and don't feel the need to come close to investigate anymore, or they have become irritated by the invasion of bubbling demons and have moved up the reef to less active areas. When diving a mid-atoll lagoon pinnacle or seaward reef slope far from inhabited islands, you're still likely to see numerous grays.