The island
Juani lies east of Chole and forms the eastern wall of Chole Bay, which is the reason the bay is sheltered at all. It is inhabited — the marine park’s management plan records a population of 998, wholly inside the park — and it carries the ruins of Kua, the town that was the centre of the archipelago before Chole was.
No published figure for the island’s land area could be found. That is unusual enough to state rather than to paper over with an estimate.
Turtles, which is what makes it nationally important
Juani carries the largest green turtle rookery in Tanzania, and the numbers behind that claim are published rather than asserted.
There are eight nesting beaches on the eastern side of the island. More than 60 per cent of all green turtle nests laid inside Mafia Island Marine Park are laid here, and more than half of all recorded green turtle nests in the whole country. The historical average is 124 nests a year, give or take 45. In the 2012 peak season, 60 nesting attempts were recorded, 50 of them successful, by 18 individual females; the annual nesting population is estimated at 41 to 72 animals. Community-based monitoring has run since 2001 through a local conservation officer trained by the marine conservation organisation working on this coast.
The whole eastern seaboard is a specified-use zone in the park’s plan, bounded fifty metres above the high-water mark inland and a kilometre seaward, precisely because those beaches matter. The park also records that turtles here are vulnerable to capture in shark nets in the waters off the outer reef, particularly during nesting.
The practical consequence is that this is not a beach you wander onto. Nesting beaches on this coast are not signposted attractions and access, where it exists at all, runs through the monitoring programme — the sea turtle guide sets out how that works. Peak nesting is April to June and hatchlings emerge roughly June to September.
The mangrove channel
The water channel at Juani’s south-western corner, known locally as Mto wa Kizani, is a separate core zone. The park describes it as a site of scenic beauty used for tourism, lined with mature mangroves that have begun to suffer from uncontrolled cutting, with large flocks of waders and small seabirds using the intertidal area. It is one of the better mangrove and paddling stretches in the archipelago.
A tidal channel at the southern end of the island is sold as the Blue Lagoon and is said to be reachable only around high water. That description comes from the travel trade rather than from the park, and the name is shared with at least two other places on this coast — including one on Unguja.
The cave, which is not the ruins
Ukunju Cave on Juani is a genuine Iron Age occupation site with published archaeology behind it, and it is a separate thing from the Kua ruins. Listings frequently merge them into “the caves at Kua”. The marine park’s own account places the island’s other caves in the Mlola forest on the main island, not at Kua.
Common questions about Juani
Why is Juani important?
It holds Tanzania’s largest green turtle rookery — eight nesting beaches on its eastern side taking more than 60 per cent of the marine park’s green turtle nests and more than half the country’s — and it carries the Kua ruins.
Can I visit the turtle beaches?
Not as a signposted attraction. The whole eastern seaboard is a specified-use zone for that reason, and access where it exists runs through the monitoring programme. Peak nesting is April to June; hatchlings emerge roughly June to September.
Is Juani inhabited?
Yes — 998 people, all inside the marine park.
Are the caves part of the Kua ruins?
No. Ukunju Cave is an Iron Age occupation site with its own published archaeology. Listings that offer “the caves at Kua” have merged two separate things.