The Great Blue Hole inside Lighthouse Reef

The Great Blue Hole inside Lighthouse Reef is an original illustration set in Great Blue Hole, Lighthouse Reef, Belize. It lies in the tropics, where the climate is tropical savanna — a pronounced dry season.

A near-vertical aerial view shows the Great Blue Hole as an almost perfect indigo circle surrounded by a narrow turquoise reef ring. Pale coral patches and white wave lines mark the outer atoll lagoon, two tiny boats establish the immense scale, and a small mangrove caye sits well outside the circle without breaking its clean geometry.

Why does a near-perfect dark circle open inside a shallow turquoise reef?

The dark center is a flooded limestone sinkhole that formed when sea level was lower and rainwater dissolved a cavern system. Rising post-glacial seas submerged the cavity, while corals continued growing in the sunlit shallows around its rim but not across the deep interior. That abrupt depth change absorbs more light and creates the dark disk; the turquoise collar and breaking outer reef reveal that the hole lies within a much larger living atoll platform.

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