Mafia Island
Tanzania · Indian Ocean
Mafia Island Marine Park in Tanzania's Chole Bay protects a mosaic of coral gardens, seagrass beds, and offshore reefs where whale sharks aggregate October through February and nesting green and hawksbill turtles return year after year — the dry season from June to October brings exceptional visibility.
How this reef is doing
ⓘ How we measure thisReef state
Live coral covers 20% of this reef.
Coral cover
Fish life
Heat
Fishing
Open to fishing, and the water is fairly quiet.
Sources · MERMAID and the survey teams · Global Fishing Watch and reef gravity
Coral cover over time
Live coral cover, by survey year
Across surveys in 2024 and 2025, live coral cover here has fallen from 52% to 20%. Every point is a real survey reading, never a projection.
Live coral cover, percent by year
| Year | Coral cover |
|---|---|
| 2024 | 52% |
| 2025 | 20% |
What you will see
17 species across the dive sites here
Whale Shark
Seen 6 months ago
at Kinasi Wall
Endangered
Miller'S Nembrotha
Seen 9 months ago
at Kinasi Wall
Allard'S Anemonefish
Seen 9 months ago
at Forbes Bay
Least concern
Green Turtle
Seen Jul 2025
at Ras Kisimani
Least concern
Leaf Scorpionfish
Seen Mar 2025
at Kinasi Wall
Least concern
Common Seahorse
Seen Jun 2024
at Kinasi Wall
Vulnerable
Coleman Shrimp
Seen year round
at Chole Bay Gardens
Giant Moray
Seen year round
at Kinasi Wall
Least concern
Giant Trevally
Seen year round
at Ras Kisimani
Least concern
Hawksbill Sea Turtle
Seen year round
at Forbes Bay
Critically endangered
Lionfish
Seen year round
at Kinasi Wall
Least concern
Longnose Hawkfish
Seen year round
at Forbes Bay
Least concern
Pygmy Seahorse
Seen year round
at Chole Bay Gardens
Least concern
Spanish Dancer
Seen year round
at Chole Bay Gardens
Spotted Eagle Ray
Seen year round
at Kinasi Wall
Endangered
Blue Dragon
Seasonal visitor
at Forbes Bay
Scalloped Hammerhead
Seasonal visitor
at Ras Kisimani
Critically endangered
Dive sites
Kinasi Wall
whale shark · spotted eagle ray · lionfish · giant moray
Forbes Bay
hawksbill sea turtle · leaf scorpionfish · longnose hawkfish · common seahorse
Ras Kisimani
scalloped hammerhead · giant trevally · green turtle · common seahorse
Chole Bay Gardens
pygmy seahorse · spanish dancer · coleman shrimp · common seahorse