Darwin's Arch (Darwin's Pillars)

The famous rock arch beside Darwin Island collapsed in May 2021, leaving two pillars, but the dive below never depended on the architecture. Divers drop onto a boulder platform at 12-20 m nicknamed the theater, brace against the current, and watch the eastern Pacific commute past: scalloped hammerheads in ranks, Galapagos sharks quartering the edge, turtles laboring across the flow. In the cool season the main event arrives from the blue - whale sharks, most of them enormous females, that pass the platform on patrol. The ascent drifts into open water, blue and bottomless, which is where safety-stop silkies like to make their inspection.

The moment you come for: Whale sharks June-November, walls of hammerheads, Galapagos sharks at arm's length, dolphin flybys

Topography: Sloping boulder platform ending in a drop to deep water

Current: Current sets the plan; divers wedge in behind boulders on the platform, then drift off into the blue for the ascent.

Hazards: Strong current, surge over the platform, blue-water ascents far from the boat; panga pickups require a DSMB.

Conservation: Within the Galapagos Marine Reserve; no contact with the reef, and only permitted liveaboards may dive here.

Nitrox: Worth it here: profiles sit in the range where enriched air meaningfully extends no-stop time (with the training to use it).