Dolphin Watching at Kizimkazi and Menai Bay

What dolphin watching in Zanzibar actually involves

Almost all organised dolphin watching in Tanzania happens in one place: the water off Kizimkazi, at the southern tip of Unguja, inside Menai Bay. A fleet of small open boats leaves the fishing village early, runs out to where the dolphins are, and follows them. On most trips, when a group is found, passengers are told to put on masks and get into the water.

That last part is the reason this activity needs more than a description. Dolphin watching in Zanzibar is not the same thing as whale watching from a distance, and it is not a passive activity. It is, in the form it is usually sold, a swim-with activity conducted on wild, resident, unhabituated animals by a large number of boats in a small area, with no formal regulation governing how they behave.

This coast sits beside Tanzania's safari country rather than inside it, and a dolphin morning belongs to a beach week. The rest of this guide sets out what the research on these particular animals has found, why the activity works the way it does, and what separates a boat worth getting on from one that is not.

The animals, and how few of them there are

Two species live in Menai Bay year round. The Indo-Pacific bottlenose dolphin, Tursiops aduncus, is the one most trips encounter. The Indian Ocean humpback dolphin, Sousa plumbea, is shyer, less often seen and considerably rarer.

A study published in 2016 estimated the bay's populations at about 136 bottlenose dolphins, with a confidence interval of 124 to 172, and about 63 humpback dolphins, with an interval of 57 to 95. Those are not large numbers. They are not passing pods drawn from an ocean-wide population; they are a small, resident, identifiable community of animals living in a defined bay, and the same individuals are encountered repeatedly.

The same study found that detection and foraging activity were significantly higher at night than during the day across all its monitoring sites, and that foraging rose on flood tides and at high water. Dolphin tourism, by contrast, operates entirely in daylight.

What the research found

This has been studied more than most wildlife tourism in East Africa, and the findings are consistent enough to state plainly.

A 2010 study in Endangered Species Research by Christiansen, Lusseau, Stensland and Berggren compared the behaviour of Indo-Pacific bottlenose dolphins off southern Zanzibar with and without tourist boats present. With boats present, the dolphins were less likely to remain resting or socialising and more likely to start travelling or foraging. Across the behavioural budget, resting, socialising and foraging all decreased and travelling increased. The authors noted the energetic implications of that shift, concluded that the level of tourism then operating was affecting the animals' cumulative behavioural budget, and wrote that regulations on dolphin tourism were urgently needed.

The 2016 study went further. Its authors found evidence consistent with a partial distributional shift away from the main tourism area during daylight hours, which they interpreted as possible displacement from previously favoured habitat. They also recorded that no formal management currently protects these populations from either fisheries bycatch or tourism.

Two things are worth being precise about here, because this is an area where advocacy on both sides overstates.

First, none of this research reports dolphins being killed or injured by tourism. What it reports is disturbance: animals interrupted while resting and feeding, doing so repeatedly, in the one bay they live in, with the energetic cost that implies for a small population.

Second, the problem is not that people look at dolphins. It is the intensity and the manner. A large number of boats converging on a group, manoeuvring to get ahead of it, and repeatedly putting swimmers into the water on top of it is a different activity from watching from a distance, and the research is measuring the first one.

Why it works this way

It would be easy, and wrong, to write this as a story about bad operators. The dynamic is structural and the socio-economics have been studied too: a survey of Kizimkazi's dolphin tourism covered fifty boat operators, six restaurant managers and hoteliers, fifty residents, three dive business managers and two hundred and seventy tourists.

The picture that emerges is of a village economy that has become substantially dependent on this one activity. Boat operators are competing directly with each other on the water for a finite number of dolphin groups. Visitors arrive having paid for a trip whose selling point, frequently stated explicitly, is swimming with dolphins. A captain who hangs back, keeps his distance and does not put people in the water loses out to the boat next to him that does, and gets the poor review.

That is the engine. Individual restraint is commercially penalised, and there is no regulation to equalise it. It also means that the single most effective thing a visitor can do is remove the reward: make it clear, before money changes hands, that you are paying for a well-conducted trip rather than a guaranteed swim, and that you will not mark the trip down if the dolphins are left alone.

What separates a well-run trip from a badly run one

There is no licensing regime here that does this work for you, so it comes down to the individual crew. The difference is visible from the boat within ten minutes.

A badly run trip looks like this. Several boats converge at speed on a group. Engines rev to cut across the animals' line of travel. Passengers jump in, often directly in front of the dolphins, and the boat repositions to do it again as soon as the group moves off. The dolphins change direction repeatedly. Nobody briefs anybody on anything except when to jump.

A well-run trip looks like this. The boat approaches slowly and from the side or behind, never head-on, and holds a distance. It does not cut in front. The engine goes into neutral or off when animals are close. The crew watches what the group is doing and can tell you whether it is travelling, feeding or resting, and backs off from a resting group. If swimmers go in, they enter quietly off the side rather than jumping, stay together, do not swim at the animals and do not attempt to touch them. The number of attempts is limited rather than repeated until the boat's time is up. And when the dolphins leave, the boat lets them.

The other tell is what the crew says before you leave the beach. An operator who explains in advance that dolphins are wild, that sightings are not guaranteed, that swimming may not happen, and that the boat will not chase, has told you a great deal about how the morning will go.

The questions to ask before you book

This site does not rank operators, recommends none, and takes no view on which is better. It can tell you what to ask, and the answers are informative even when they are evasive.

• Do you put people in the water, and under what circumstances do you decide not to?
• How close does the boat go, and do you approach from behind and to the side rather than in front?
• What do you do if the dolphins are resting?
• How many attempts will we make before leaving the group alone?
• Is the engine off or in neutral while animals are close to the boat?
• What happens if we do not find dolphins at all?
• Will there be a briefing on conduct in the water before we leave?
• How many boats do you work alongside, and do you wait your turn or join a group that already has boats on it?

Two further points. Be explicit at the point of booking that you would rather see dolphins behaving normally at a distance than swim with harassed ones, because that is the signal that changes behaviour. And if the trip you are on turns into a chase, you are entitled to ask the captain to back off. It is your morning and you paid for it.

Be equally wary of the opposite marketing. A growing number of trips are sold on the word "ethical" with nothing behind it, and this guide cannot and will not tell you which operators deserve the label. The questions above are the only reliable test, and the answers are given before you pay.

Seeing dolphins without booking a dolphin trip

This is the part most guides leave out, and for many visitors it is the better answer.

Dolphins are seen regularly, and incidentally, from other boats on this coast. A snorkelling trip, a dhow sail, a fishing charter or a dive boat will frequently encounter them, and an encounter with a boat that is not pursuing them is a completely different thing to watch. The dolphins behave normally, because nothing is being done to them.

Bottlenose dolphins also occur elsewhere along the Tanzanian coast, off Mafia, around Pemba, off the mainland and in the Dar es Salaam island waters, without an organised industry attached. Spinner dolphins are seen offshore in deeper water. None of that is a scheduled activity you can book, which is precisely why it is unmanaged in the opposite direction.

If you do want to go out specifically to see dolphins, consider asking for a boat that will watch without swimming. Some crews will do this, some will not understand why you want it, and the conversation itself tells you which kind of operation you are dealing with.

Season, timing and what you will actually see

The dolphins are resident and present all year, so there is no season in the sense that whale sharks or humpbacks have one. What varies is the sea state and the number of other boats.

Trips leave early, generally soon after dawn, for two reasons: the wind gets up later and the boats want to be first out. The sea off the southern tip is calmer under the lighter north-easterly kaskazi winds from roughly December to March and rougher under the south-easterly kusi from around June to September, when it can be a genuinely uncomfortable small-boat ride. The long rains here run from around March to May and many operations close for part of them.

What you will actually see, on a good morning, is a group of dolphins travelling or feeding, surfacing, occasionally bow-riding, and generally at the surface for only a few seconds at a time. What you will probably not get is the photograph on the poster. Water clarity in the bay is variable, dolphins underwater are fast and rarely stay near a swimmer, and most in-water encounters last a handful of seconds.

Sightings are not guaranteed, and a morning can end without them. That is the nature of wild animals, and any promise otherwise is worth treating as a description of how the boat intends to behave rather than as a fact about the sea.

Common questions about dolphin watching in Zanzibar