Bajo Alcyone

Located in the late 1980s by Jacques Cousteau's team and named for their turbosail ship Alcyone, then made famous by decades of shark research, Bajo Alcyone is the purest expression of what Cocos does. The seamount's summit levels off around 27 m; divers pull themselves down the mooring line through the blue, wedge in among barnacle-crusted rocks, and wait. Barberfish rise to meet incoming scalloped hammerheads, and on the good days the school builds overhead until it dims the surface light. Marbled rays sail past like flying carpets, whitetips thread the rocks, and the drifting deco stop in open water regularly produces silkies and, in season, a whale shark.

اللحظة التي جئت من أجلها: The archetypal hammerhead cleaning station, marbled rays, blue-water safety stops with silkies

التضاريس: Flattened volcanic summit at 25-30 m dropping into deep water

التيار: Descend the line, get behind rock, stay low; the current is what delivers the sharks.

المخاطر: Depth plus current plus blue-water ascent - a dive to plan conservatively, 36 hours from help.

الحفاظ على البيئة البحرية: Cocos Island National Park; no gloves on the reef, no contact, ranger-monitored moorings.

نيتروكس: يستحق هنا — تقع البروفايلات في النطاق الذي يمدّد فيه النيتروكس وقت التوقف اللاإلزامي بشكل ملموس (بشرط امتلاك التدريب اللازم لاستخدامه).