OBSERVATION / 013

A dark circle in the reef.

EO-1 satellite view of turquoise Lighthouse Reef off Belize, with a small dark circular Blue Hole amid shallow water and scattered clouds.

NASA Earth Observatory / Jesse Allen · NASA EO-1 Team

Location: Great Blue Hole / Lighthouse Reef / Belize
Image acquired: March 24, 2009
Platform / instrument: Earth Observing-1 / ALI
Image type: Satellite image

Field notes

A small dark circle breaks the pale turquoise water of Lighthouse Reef off Belize. The Great Blue Hole is a deep flooded cave within a much shallower reef system, visible in this March 2009 satellite image.

The feature is roughly 300 meters across and about 125 meters deep. Stalactites inside it formed when sea level was lower and the cave stood above water. The contrast seen from orbit comes from deep water beside shallow water over light-colored coral.

Read NASA’s full account ↗

This is dated source imagery. The homepage overlay is a graphic treatment, not a georeferenced measurement.