Located roughly 40 miles off the Belize coast, the Blue Hole is thought to have once been a giant cave on dry land, thousands of years ago.
As the ocean rose again, the cave flooded. It's now part of the wider Belize Barrier Reef Reserve System, which is a UNESCO World Heritage Site.
The Blue Hole has never been fully mapped or plotted -- the idea is this new expedition might answer the question of what lies at the bottom of this enigmatic cavern.
One of the submersibles on the expedition will have additional lighting to allow both the on board team and the viewer at home to see as much as possible.
There are also two support vessels on site, a luxury charter yacht providing accommodation and amenities for the team and a research vessel to support the expedition.
Following the dive on December 2, vessels will continue to monitor and explore the site for two weeks, collecting data that will allow experts to construct real-life models of the Blue Hole's geography.