Kelleston Drain — Speyside

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Overview

Drift dive off the southern flank of Little Tobago, 3 km east of Speyside, ending at the largest documented brain coral colony on Earth — a boulder brain (Colpophyllia natans) roughly 3 m tall and 5 m across, estimated to be more than two centuries old. The reef slopes from 18 m down past 40 m through forests of gorgonians, sea whips, and barrel sponges fed by nutrient-rich currents pushing up from the Guiana plume.

Briefing note

Drift profile with a moderate-to-strong cross-current is the norm — boats live-pick divers downstream, so an SMB is mandatory and a reel is recommended. The famous brain coral sits at about 18 m on a sandy shelf; do not touch or rest fins on it, the colony is fragile despite its size. Wet-season runoff from the Orinoco River (Jul–Nov) routinely drops visibility into the 10–20 m range and can turn the surface tea-colored; the dry months (Dec–Jun) are the dependable window. Site lies inside protected reef habitat managed under Tobago's marine policy — spearfishing and glove use are discouraged.

What you'll see

7 species curated

Boulder brain coral
year-round
Nurse shark
year-round
Caribbean reef shark
year-round
Manta ray
seasonal
Peak: Apr · May · Jun · Jul · Aug
Ocean triggerfish
year-round
Tarpon
year-round
Southern stingray
year-round

Sightings evidence

1 record on file

Boulder brain coral
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 We deliberately do not publish a numeric '% chance of sighting' from this data.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
OBIS-SEAMAP — Duke University Marine Geospatial Ecology Lab / OBIS
iNaturalist — California Academy of Sciences & National Geographic Society
IUCN Red List of Threatened Species — International Union for Conservation of Nature
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	26–27 °C	20–30 m	moderate
Feb	26–27 °C	20–30 m	moderate
Mar	26–27 °C	20–30 m	moderate
Apr	27–28 °C	20–30 m	moderate
May	27–28 °C	20–30 m	moderate
Jun	28–29 °C	15–25 m	moderate
Jul	28–30 °C	10–20 m	strong
Aug	29–30 °C	10–20 m	strong
Sep	29–30 °C	10–20 m	strong
Oct	28–29 °C	10–20 m	moderate
Nov	27–28 °C	15–25 m	moderate
Dec	26–27 °C	20–30 m	moderate

Season calendar

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Peak season highlighted · current month outlined

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