Snorkel Sites
Diving Depth
Marine Species
Water Temp
Best Season
Tanzania's Indian Ocean Waters Are Extraordinary
Most travellers come to Tanzania for the safari — the Serengeti, the Ngorongoro Crater, the great herds and the predators. What many do not realise is that the Indian Ocean coastline that follows Tanzania's eastern border offers one of the finest marine environments in the Indian Ocean.
Snorkelling over coral gardens at Mnemba Atoll. Diving the Pemba Channel where the reef drops to 1,000 metres and large pelagic species cruise the blue water. Swimming with juvenile whale sharks in Mafia Channel. Each of these experiences is world-class in its own right. Combined with a Tanzania safari, they create a trip of extraordinary range and depth.
This guide covers the key marine sites — both snorkelling and diving — when to go, what to expect, and how to combine a marine extension with the rest of your Tanzania trip.
1 of 6 — Marine Sites
Mnemba Atoll
Off the northeast coast of Zanzibar
A private marine conservation area 45 minutes by boat from Stone Town. The fringing reef forms a complete circle around a shallow lagoon — extraordinary snorkelling without strong currents, suitable for beginners and experienced snorkellers alike.
Marine Life
Green and hawksbill turtles, giant trevally, napoleon wrasse, moray eels, reef sharks, and over 200 species of coral fish. The atoll is a designated turtle nesting site.
Conditions
Calm conditions year-round. Best visibility October through March. Shallow reef crest (3–8m) with deeper drop-off on the outer edge.
2 of 6 — Marine Sites
Pemba Channel
Western Pemba Island
One of the world's great drift dive destinations. The Pemba Channel drops to over 1,000 metres just a few hundred metres from shore, creating dramatic upwellings that attract large pelagic species. Not for beginners.
Marine Life
Grey reef sharks, silky sharks, hammerheads, manta rays, whale sharks (Nov–Jan), schools of barracuda and big-eye trevally. Exceptional soft coral walls.
Conditions
Strong currents are the norm — experienced guide and divemaster essential. Water temperature 24–27°C. Visibility 20–40m.
3 of 6 — Marine Sites
Changuu Island (Prison Island)
25 minutes from Stone Town
A small coral island with a history as a 19th-century prison and now a giant Aldabra tortoise sanctuary. The surrounding reef is one of the most accessible snorkelling sites near Stone Town.
Marine Life
Colourful reef fish, octopus, moray eels, occasional reef sharks, and in season, dolphins pass through the channel. The coral gardens near the island's eastern edge are the most vibrant.
Conditions
Calm water, easy snorkelling. Can be affected by wind in the kaskazi season (Dec–Feb).
4 of 6 — Marine Sites
Mafia Island Marine Park
Mafia District, 120km south of Zanzibar
Mafia is Tanzania's original marine park — established in 1995 and still one of the most well-managed. The diving is concentrated around the southern reefs and the Kilindoni channel. Mafia is quieter than Zanzibar, with fewer tourists and a more authentic Swahili character.
Marine Life
Whale sharks (Oct–Mar), manta rays, sea turtles, giant groupers, and extensive coral gardens. Mafia is particularly known for its whale shark encounters — the largest fish in the sea, gently filter-feeding in the channel.
Conditions
Mild currents, clear water October through March. Chole Bay offers sheltered snorkelling for beginners.
5 of 6 — Marine Sites
Stone Town Reefs
Directly offshore from Zanzibar Town
Several accessible reef sites within 20 minutes of Stone Town, including The Livingstone Reef and nearby garden eel dive. Not the most spectacular reefs in Tanzania, but convenient for those based in Stone Town.
Marine Life
Garden eels, scorpionfish, leaf fish, nudibranchs, and macro life. The variety of smaller creatures makes this popular with underwater photographers.
Conditions
Calm water. Limited visibility during rainy season (Apr–May). Best in the kusi winds season (May–Oct).
6 of 6 — Marine Sites
Nungwi and Kendwa Reefs
Northern Zanzibar
The northern beaches of Zanzibar offer accessible shore snorkelling and boat-accessed reef diving. Nungwi and Kendwa have the most consistent diving conditions on Zanzibar's north coast, with several dive operators based here.
Marine Life
Reef fish, rays, octopus, and seasonal turtle nesting. The deeper sites (15–30m) on the outer reef offer better chances for shark encounters.
Conditions
Generally calm year-round, though kusi winds (May–Oct) can make boat trips rougher. Best visibility Oct–Mar.
Before You Go
Practical Information
Getting There
Zanzibar Airport (ZNZ) has daily flights from Dar es Salaam (30 minutes) and direct flights from Nairobi, Addis Ababa, and Dubai. From Stone Town, dive boats depart early morning. Mafia Island is reached by a 20-minute flight from Zanzibar or a 4-hour boat crossing.
Certification & Safety
Ensure your dive operator holds current PADI or SSI accreditation and that guides hold recognised divemaster or instructor credentials. Ask to see certification cards. Tanzania has no formal dive insurance requirement but DAN dive accident insurance is strongly recommended — helicopter evacuation from remote sites is expensive.
When to Book
For diving during peak season (December–February), book dive operators at least 4–6 weeks in advance — the best guides and boats fill quickly. For snorkelling-focused trips, you can book more last-minute. Mafia Island is quieter and more flexible.
What to Bring
Reef-safe sunscreen (no oxybenzone or octinoxate — these are banned in Mafia Marine Park), a rash guard for sun protection during surface intervals, underwater camera if you have one, and motion sickness tablets if you are prone to seasickness on the boat rides out to sites.
Combining with Safari
The classic combination is a Tanzania northern circuit safari (Serengeti, Ngorongoro, Tarangire) followed by 3–5 days on Zanzibar. Fly from Arusha to Zanzibar in under 2 hours. Allow at least 3 days on the island to get a meaningful marine experience — one day is not enough to appreciate what the reefs offer.
Common Questions
Frequently Asked Questions
Is Zanzibar good for snorkelling if I am not a diver?
What is the difference between Zanzibar and Mafia Island for marine activities?
Is it safe to dive in Tanzania?
When is the best time to see whale sharks in Zanzibar and Mafia?
How many days do I need for a meaningful Zanzibar marine experience?
Can I combine Zanzibar marine activities with a Kilimanjaro climb?
What is reef-safe sunscreen and why does it matter?
Combine with Safari
Planning Your Tanzania Safari & Zanzibar Trip
The classic combination is a Tanzania northern circuit safari — 5 to 8 days covering Serengeti, Ngorongoro Crater, and Tarangire — followed by 3 to 5 days on Zanzibar. You fly from Kilimanjaro Airport (near Arusha) directly to Zanzibar in under 2 hours.
After the physical demands of a safari — the early mornings, the dusty roads, the wildlife tension — the warm, calm waters of Zanzibar are exactly what the body ordered. No alarm clocks, no 5am game drives, just turquoise water, soft sand, and extraordinary reef life within swimming distance of shore.
For those who have climbed Kilimanjaro, Zanzibar as a post-climb recovery destination is almost medicinal. The mountain and the ocean — two of Earth's most extraordinary environments in one trip.
Ready to Plan?
Talk to Our Planning Team
Ready to Explore Tanzania's Marine World?
We can plan the safari-to-beach combination that is right for you — with advice on the best marine sites for your interests, the right dive operator, and the logistics of combining Tanzania's best wildlife with its best coastline.