Great Blue Hole — The Pit

Planning a trip?

Hotels, dive operators, gear, and how to get here are on the The Pit location page.

Overview

Cousteau's famous circular sinkhole, 300 m across and 125 m deep, off Lighthouse Reef. The dive descends past 30 m where massive stalactites lean from the rim — relics of a dry cave that collapsed when sea levels rose. More geology trip than reef dive; the deep, dark profile is the draw.

Briefing note

Once-in-a-lifetime geology dive — accept that marine life is sparse below the rim.

What you'll see

3 species curated

Caribbean reef shark
year-round
Midnight parrotfish
year-round
Bull shark
rare

Sightings evidence

1 record on file

Caribbean reef shark
high confidence
Last confirmed
May 2026
Recent records
130 within 10 km

Sources & methodology

How we summarise this

We aggregate confirmed occurrence records from GBIF and OBIS within a fixed radius of each dive site. Occurrence records confirm presence and reveal seasonality clustering, but they DO NOT measure per-dive probability — there is no eligible-effort denominator. We deliberately do not publish a numeric '% chance of sighting' from this data.

Sources

Global Biodiversity Information Facility — GBIF Secretariat
Ocean Biodiversity Information System — IOC-UNESCO
iNaturalist — California Academy of Sciences & National Geographic Society
IUCN Red List of Threatened Species — International Union for Conservation of Nature
Wildbook (Sharkbook, Whale Shark, Manta Matcher) — Wild Me
OBIS-SEAMAP — Duke University Marine Geospatial Ecology Lab / OBIS
WoRMS — World Register of Marine Species — Flanders Marine Institute (VLIZ)
FishBase — FishBase Consortium
Atlas of Living Australia — CSIRO / GBIF Australia
REEF Volunteer Fish Survey — Reef Environmental Education Foundation

Conditions

Month	Water	Visibility	Current
Jan	25–26 °C	20–35 m	mild
Feb	25–26 °C	20–35 m	mild
Mar	26–27 °C	25–40 m	mild
Apr	26–27 °C	25–40 m	mild
May	27–28 °C	25–40 m	mild
Jun	28–29 °C	20–35 m	mild
Jul	28–29 °C	20–35 m	mild
Aug	28–29 °C	20–35 m	mild
Sep	28–29 °C	15–30 m	mild
Oct	27–28 °C	15–30 m	mild
Nov	26–27 °C	20–35 m	mild
Dec	25–26 °C	20–35 m	mild

Season calendar

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Peak season highlighted · current month outlined

Gear for this site

Beyond the basic kit

Dive computer — Deep no-deco profile with a tight ascent margin.
Dive light — Stalactite chamber sits in deep shadow below 30 m.

Next step

Book your trip to The Pit

Hotels, liveaboards, dive operators, gear recommendations, and travel logistics for the whole region.

Plan your trip →

Some links earn us a commission. Learn more