Short answer: The Blue Hole depths vary by location. The best-known examples are around 100–130 meters deep (roughly 328–430 feet) in the Red Sea and off Belize, though newer discoveries have claimed deeper holes elsewhere. Details to help you:

• Red Sea Blue Hole (Egypt, near Dahab): maximum depth just over 100 m (328 ft). Access points include a shallow saddle around 6 m and a tunnel called “the Arch” whose ceiling sits near 55 m with a bottom clearing to about 120 m on the seaward side.

• Belize Great Blue Hole: commonly cited depth around 124 m (407 ft). It’s a large circular sinkhole 318 m across located on Lighthouse Reef atoll.

• Mexico’s Taam Ja’ Blue Hole (Chetumal Bay): recent measurements have pushed reported depths beyond 420 m (about 1,380 ft) in some sources, making it one of the deepest reported blue holes; researchers caution bottom measurements may still be incomplete due to challenging conditions.

• Other notes: depths are often reported as “maximum depth” for the hole itself, while some routes (arches, tunnels) within the hole reach different depths, sometimes shallower than the deepest point.

If you’re after a specific Blue Hole, tell me which one (location) and I can provide the most widely cited depth and any notable features (entrances, tunnels, or measurement caveats). Sources and context:

• Red Sea Blue Hole depth and features (maximum depth ~100 m; saddle and Arch details).

• Belize Great Blue Hole dimensions and depth ~124 m, with discovery context from later expeditions.

• Taam Ja’ Blue Hole in Mexico-Chetumal Bay with deeper reported measurements and caveats about bottom reach.

• Additional Belize and related blue hole depths and features for cross-reference.