Caribbean · Saint Vincent and the Grenadines
Union Island & the Tobago Cays
Green turtles and a horseshoe barrier reef in the Tobago Cays Marine Park
Photo: Don Loarie · CC BY 4.0
Union Island sits in the centre of a group of reef-fringed islands in the Southern Grenadines, and its dive boats run to the Tobago Cays Marine Park, Mayreau, Petit St. Vincent and Mopion. Most dives run from 6 m to 24 m (20–80 ft) over Horseshoe Reef, the drift at Mayreau Gardens and the Puruni, a naval trawler wrecked in 1918. The highlight is the Tobago Cays: a protected lagoon behind a horseshoe of reef where green turtles live and sharks are sighted on dives regularly.
About diving in Union Island & the Tobago Cays
Dives go out by high-speed boat: the surrounding islands are visible in almost every direction and are reached in a few minutes. Groups are small and divers help choose the day's sites. Inside the Tobago Cays Marine Park, diving is limited to registered local dive shops, and the park charges user fees. Sail Rock is very exposed, so it is dived only in good weather. Hurricane Beryl devastated Union Island in July 2024 and left most of its infrastructure in ruins.
Many reefs sit at 9–12 m (30–40 ft), and most are surrounded by white sand that catches the sunlight and brightens the colours. Horseshoe Reef offers a protected, shallow inside and a deeper drop-off on the outside. Mayreau has the most sites: the Valley Dive holds the best coral formations and big sea fans at an average of 27 m (90 ft), and Hot Springs is an underwater volcano where bubbles rise and the water turns very warm. Crinoids, garden eels and flamingo tongues are common at Mayreau Gardens. Surveys in 2007 found most reefs dominated by dead coral rubble, with live coral cover between 5% and 30%, and all are considered to be in decline.
The area suits new and relaxed divers: most dives are easy, Petit Tabac suits resort courses, the Puruni wreck works for beginners and advanced wreck divers alike, and instruction runs from resort courses to full certification. Experienced divers have the current-dependent drift at Mayreau Gardens, the deep Valley Dive and Sail Rock, a pinnacle with strong currents at about 21 m (70 ft) that is for advanced divers only.
Best time to dive Union Island & the Tobago Cays
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Prime | Prime | Prime | Prime | Fair | Fair | Fair | Fair | Fair | Fair | Fair | Prime |
The high season runs from November to April. The rainy season starts in May and lasts until November, so December to April is the dry stretch of the high season. From July to October hurricanes threaten the islands. The sea runs from about 27 °C in February to about 30 °C in September.
Dive types & marine life
Green turtles live in the Tobago Cays, and sharks are sighted on dives regularly: Caribbean reef sharks and nurse sharks at Mopion Reef, nurse sharks under the ledges of Horseshoe Reef. Ends Reef is the place for squadrons of spotted eagle rays, and Round About Reef has stingrays and the occasional manta ray.
- Reef
- Drift
- Wall
- Wreck
- Sea turtles
- Reef sharks
- Eagle rays
- Stingrays
Best dive sites in Union Island & the Tobago Cays
- 1
Horseshoe Reef
Barrier reef around four of the five Tobago Cays, with nurse sharks sleeping under its ledges
- 2
Mayreau Gardens
Expansive coral reef drifted north at 17 m (55 ft) or south at 24 m (80 ft), with the current
- 3
Puruni Wreck
A naval trawler sunk off Mayreau in 1918, in 12 m (40 ft) of water, for beginners and advanced wreck divers
- 4
Sail Rock
Exposed pinnacle with a cave of several exits, schools of fish and an old cannon, for advanced divers
- 5
Mopion Reef
Reef off Petit St. Vincent with Caribbean reef sharks, nurse sharks and huge lobsters
- 6
Ends Reef
Reef where squadrons of spotted eagle rays swim in formation
- 7
Round About Reef
Easy coral reef at 6–15 m (20–50 ft) with stingrays and the occasional manta ray
- 8
Petit Tabac
Resort-course site in the Tobago Cays with a maximum depth of 14 m (45 ft)
Site guides
Nurse sharks asleep under the ledges of the Tobago Cays barrier reef
One of the two most biodiverse reef areas of the Tobago Cays park, dived as a drift
Caribbean reef sharks and huge lobsters off Petit St. Vincent
Reef
A resort-course reef around one of the five Tobago Cays
Wreck
A 1918 naval trawler turned artificial reef off Mayreau
How to get to Union Island & the Tobago Cays
Union Island Airport has domestic flights to St Vincent and other Grenadines islands and international flights to Barbados, Carriacou, Grenada and Martinique. The fast ferry from Kingstown takes 2.5 hours, stopping at Bequia, Canouan and Mayreau. Grenadines Dive is based in Clifton, and a centre on Canouan also arranges dives at the Cays.
Dive videos
Dive Grenadines Boat Sailing Out of Union Island, Grenadines, and into the Tobago Cays MP · lewnwdc on YouTube
Questions divers ask
Can divers explore the Tobago Cays without a local dive shop?+
No. Diving inside the Tobago Cays Marine Park is limited to registered local dive shops, and the park charges user fees, so dives there are booked through an operator on Union Island or a neighbouring island.
How do divers get to Union Island?+
Union Island Airport has flights from St Vincent, Barbados, Grenada, Carriacou and Martinique. The fast ferry from Kingstown takes 2.5 hours with stops at Bequia, Canouan and Mayreau, and the Union Island dive centre is based in Clifton.
Is Union Island good for beginner divers?+
Yes. Most dives are easy, Petit Tabac suits resort courses and has a 14 m (45 ft) maximum, the Puruni wreck sits in 12 m (40 ft), and instruction runs from resort courses to full certification. Sail Rock is the exception, for advanced divers only.
Where are sharks seen around Union Island?+
Mopion Reef off Petit St. Vincent has Caribbean reef sharks and nurse sharks resting on the sand, and nurse sharks sleep under the ledges of Horseshoe Reef in the Tobago Cays.
Sources
- Grenadines Dive — Grenadines Dive
- Canouan Scuba Center — Canouan Scuba Center
- Dive Sites — Government of Saint Vincent and the Grenadines, Ministry of Tourism
- Diving & Watersports — Government of Saint Vincent and the Grenadines, Ministry of Tourism
- Tobago Cays — Wikipedia
- Union Island — Wikipedia
- Union Island — Wikivoyage
- Saint Vincent and the Grenadines — Wikivoyage
- Scuba Diving with Grenadines Dive — Grenadines Dive
- About The Grenadines — Grenadines Dive
- Port Elizabeth Average Sea Temperatures — seatemperature.org
Photo credits
- One tan electric ray lying flat on grey sand, seen from above with its round disc and two small back fins. by Don Loarie, CC BY 4.0, via Wikimedia Commons
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