Africa · Tanzania
Mafia Island
Juvenile whale sharks feed in shallow water off Mafia most of the year.
Photo: brittonpaul83 · CC BY-SA 2.0
Mafia Island Marine Park off Tanzania protects Chole Bay's coral gardens along with Kinasi Pass, a tidal channel through the bay's center famous for strong currents and passing pelagics. Juvenile whale sharks feed in the shallows just offshore, most reliably from October through March, while green turtles nest on the island's beaches. Dindini Wall, the only true rock wall in the area, runs from 8 to 28 m outside the bay, and over 400 fish species have been recorded on its reefs.
About diving in Mafia Island
Diving here is governed by the tide. The centres sit on Chole Bay, a wide sheltered bay on the island's eastern side whose entrance shallows enough that boats can only cross it, or dive the pass itself, on the right stage of water. Schedules shift day to day as a result. The rides are short: small open boats leave from the beach in front of the lodges, run to a site inside the bay or just beyond it, and are back before the afternoon wind gets up.
Inside the bay the diving is sheltered coral garden, hard coral heads and bommies standing on sand, with undemanding conditions and heavy fish density, which is why it keeps working when the sea outside does not. The pass is the opposite: a channel where the bay drains and fills, dived on moving water with the current doing the work. Outside, the reefs open into slopes and a rock wall, deeper and more exposed, and they want a settled sea.
The whale sharks are a separate excursion on the other side of the island, reached by road transfer to Kilindoni and then a boat that searches for animals feeding at the surface. Those encounters are on snorkel, in shallow and often plankton-thick water, and finding them is most of the exercise. Beyond that, this is an unhurried, lodge-based island with a handful of operators and no liveaboard traffic, which suits divers content to plan a week around tide and weather.
Best time to dive Mafia Island
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Season | Prime | Prime | Fair | Fair | Fair | Good | Good | Good | Good | Prime | Prime | Prime |
| Sea surface | 29°C84°F | 29°C84°F | 30°C86°F | 29°C84°F | 28°C82°F | 27°C81°F | 26°C79°F | 26°C79°F | 26°C79°F | 27°C81°F | 28°C82°F | 29°C84°F |
| Daytime high | 29°C84°F | 29°C84°F | 30°C86°F | 29°C84°F | 29°C84°F | 28°C82°F | 27°C81°F | 26°C79°F | 27°C81°F | 28°C82°F | 29°C84°F | 30°C86°F |
| Rain | 136 mm5.4 in | 85 mm3.3 in | 189 mm7.4 in | 284 mm11.2 in | 173 mm6.8 in | 29 mm1.1 in | 15 mm0.6 in | 11 mm0.4 in | 14 mm0.6 in | 48 mm1.9 in | 84 mm3.3 in | 104 mm4.1 in |
| Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|
| Prime | Prime | Fair | Fair | Fair | Good |
| Sea surface | |||||
| 29°C84°F | 29°C84°F | 30°C86°F | 29°C84°F | 28°C82°F | 27°C81°F |
| Daytime high | |||||
| 29°C84°F | 29°C84°F | 30°C86°F | 29°C84°F | 29°C84°F | 28°C82°F |
| Rain | |||||
| 136 mm5.4 in | 85 mm3.3 in | 189 mm7.4 in | 284 mm11.2 in | 173 mm6.8 in | 29 mm1.1 in |
| Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|
| Good | Good | Good | Prime | Prime | Prime |
| Sea surface | |||||
| 26°C79°F | 26°C79°F | 26°C79°F | 27°C81°F | 28°C82°F | 29°C84°F |
| Daytime high | |||||
| 27°C81°F | 26°C79°F | 27°C81°F | 28°C82°F | 29°C84°F | 30°C86°F |
| Rain | |||||
| 15 mm0.6 in | 11 mm0.4 in | 14 mm0.6 in | 48 mm1.9 in | 84 mm3.3 in | 104 mm4.1 in |
2011–2025 averages. Sea surface: NOAA Coral Reef Watch, measured at the surface, so deeper water can run colder. Daytime high and rain: NASA POWER.
Whale shark season peaks October-March; the March-May long rains bring rougher seas and reduced visibility.
Best months: January, February, October, November, December
Mafia Island water temperature and weather by month
The sea surface runs from 26 °C (79 °F) in August to 30 °C (86 °F) in March. Most rain falls from March to May, peaking at about 280 mm (11 in) in April; it stays largely dry from June to October. Daytime highs reach 30 °C (86 °F) in March and drop to 26 °C (79 °F) in August. The coldest water here is about 25 °C (77 °F), so pack a 3 mm full suit.
Dive types & marine life
Whale sharks are the draw from October into March, when juveniles feed near the surface off the island. The reefs run steadier year-round: dense schooling reef fish, trevally hunting along the pass, turtles over the coral gardens and dolphins seen from the boat. The long rains from March into May bring rougher, greener water rather than a halt to diving.
- Reef
- Coral garden
- Wall
- Drift
- Whale sharks
- Sea turtles
- Reef fish swarms
- Pristine corals
- Trevally & jacks
- Dolphins
Best dive sites in Mafia Island
Reef
The north end of an 800 m reefbank, 5 m to sand at 17 m
Reef
Reef rays resting on the rubble at the foot of the reef
Wall
A coral bank to 15 m, dived by day and after dark
Coral garden
Three coral patches divided by bright sand channels
Wall
An archway in the rock wall, ringed by reef fish
Wall
A vertical face with shallow caverns, 8 m to 26 m
Reef
Pink and purple corals down a seaward reef slope to 26 m
Channel & pass
The channel through the centre of Chole Bay, dived as a drift
Drift
A drift along a coloured coral slope to 25 m
Reef
Coral bommies on white sand, from 5 m down to 17 m
Pinnacle
Coral towers rising from 18 m to just under the surface
Wall
Sheer little walls from 3 m to 17 m, thick with sponges
Reef
A shallow reef inundated with nudibranchs, 300 m off the beach
Pinnacle
Pinnacles lit side-on by the dawn light, 3 m to 16 m
Pinnacle
A coral spire from 24 m to just under the surface
Drift
Mafia's adrenaline dive, run in a very strong current
Tutia Reef
Coral formations off Juani Island known for fish diversity.
How to get to Mafia Island
The standard route is a light aircraft from Dar es Salaam to the island's airstrip at Kilindoni, then a road transfer across to the Chole Bay lodges at Utende, where the dive centres are. Marine park entry is charged as a daily fee and usually settled through the lodge. All diving is by boat.
Photos from Mafia Island
Ewout Knoester · CC BY-SA 4.0
brittonpaul83 · CC BY-SA 2.0
brittonpaul83 · CC BY-SA 2.0
brittonpaul83 · CC BY-SA 2.0
Dive videos
From Nudibranchs to Whale Sharks | Diving in Mafia Island | Chole Bay Tanzania 2021 | 4K-Video · Bird & Wildlife Adventures on YouTube
Scuba diving - Mafia Island, Tanzania · Fredrik Lundberg on YouTube
Photo credits
- Orange anthias fish swarm over a colourful coral garden on Mafia Island's reef by brittonpaul83, CC BY-SA 2.0, via Openverse
- A black and yellow striped orange-lined nudibranch crawls over the reef in Tanzania by Ewout Knoester, CC BY-SA 4.0, via Wikimedia Commons
- A giant clam with a wavy green and gold mantle is embedded in coral off Mafia Island by brittonpaul83, CC BY-SA 2.0, via Openverse
- A blue sea star spans a patch of coral rubble on Mafia Island's reef by brittonpaul83, CC BY-SA 2.0, via Openverse
- A fisherman sits in silhouette on a dhow as the sun sets over the water off Mafia Island by brittonpaul83, CC BY-SA 2.0, via Openverse
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In The Logbook
- Nudibranchs: species, habits and where to diveMacro & muck · 13 min read
- Drift diving: how to read and ride a currentDrift & current · 8 min read
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