The Great Blue Hole in Belize is about 124–125 meters deep, which is roughly 407–410 feet.

Quick facts

  • The Great Blue Hole is a large marine sinkhole located off the coast of Belize, near the center of Lighthouse Reef.
  • Its opening is about 300–318 meters (around 1,000–1,043 feet) across, making it one of the largest features of its kind in the world.
  • Early measurements put its depth at about 125 meters (410 feet), while later surveys measured around 124 meters (407 feet); both figures are often quoted.

Why the depth numbers differ

  • Different expeditions (including a 1997 Cambrian Foundation survey and later sonar mapping dives) used varying equipment and methods, which produces small measurement differences.
  • Sediment accumulation on the bottom over time can slightly change the effective depth recorded by newer surveys.

A bit of exploration context

  • The site was popularized by Jacques Cousteau in the 1970s, when his team helped chart its depth and cave formations.
  • Modern submarine and sonar expeditions in the 2010s and 2020s have mapped the sinkhole in more detail, confirming a depth a little over 120 meters with steep walls and a largely lifeless lower zone.

Information gathered from public forums or data available on the internet and portrayed here.