Visiting the Dziani Boundouni Volcanic Lake on Moheli

Dziani Boundouni occupies a volcanic crater on the eastern coast of Moheli, the smallest of the three islands forming the Union of the Comoros. Designated as Ramsar site number 717 on February 9, 1995, this 30-hectare wetland serves as a critical permanent water source in a nation where permanent rivers are largely absent. The lake sits within the Djando region, roughly 20 kilometers southeast of the capital city, Fomboni, and provides a unique habitat for specialized avian species and microbial life. Its chemical composition is influenced by subterranean volcanic upwellings, giving the water a distinct character compared to the surrounding Indian Ocean.

While Moheli receives fewer than 400 international visitors in a typical year, those who make the journey find a site largely untouched by modern infrastructure. The lake remains a raw geological feature, appearing as a still, dark eye amid the dense tropical vegetation of the island interior. Local residents from nearby Boundouni village often utilize the surrounding land for agriculture, but the lake itself remains an ecological sanctuary. Visitors should prepare for a primitive experience, as there are no paved visitor centers or manicured boardwalks surrounding the crater rim.

Geological Features and Preservation Status

Volcanic Origins of the Lake

The lake formed within a prehistoric crater and maintains a diameter of approximately 450 meters. Its water levels are sustained by a combination of rainfall and subterranean volcanic vents that push mineral-rich water upward from deep within the earth. This process creates a specific limnological environment where salinity and sulfur levels can fluctuate depending on seismic activity and seasonal precipitation. Unlike the more famous Lake Dziani on the neighboring island of Mayotte, Boundouni has a more secluded atmosphere, shielded by steep crater walls that rise sharply from the water line.

Geological surveys suggest that the ancient lake may have deep-seated connections to the ocean through porous volcanic rock. This potential link helps explain why the water level remains relatively stable even during the intense dry season from May to October. The sediment at the bottom of the lake is rich in volcanic minerals, which prevents the growth of most common aquatic plants but supports a unique community of sulfur-tolerant microorganisms. These microbes often cause subtle changes in the water color, which can shift from a deep indigo to a murky green after heavy rains.

Ramsar Convention Protection

International recognition came in the mid-1990s when the site was added to the list of Wetlands of International Importance. This designation was based on the lake's role as one of the very few stable freshwater or brackish ecosystems in the Comoro archipelago. Protection efforts focus on maintaining the integrity of the crater walls and preventing runoff from local vanilla and clove plantations from contaminating the water. The surrounding 30 hectares are managed under a framework that encourages sustainable use by local communities while forbidding industrial development.

Conservationists monitor the site primarily for its importance as a stopover for migratory birds traversing the Mozambique Channel. Because the Comoros islands are volcanic and porous, surface water is a rare commodity, making Dziani Boundouni a vital oasis. The lack of heavy tourism actually helps preserve the fragile balance of the crater, though it also means that monitoring and enforcement of environmental regulations depend largely on the local village elders rather than national park rangers.

Birdwatching and Biodiversity

Avian Habitats and Migration

The primary draw for nature enthusiasts is the concentrated bird population that gathers around the crater rim and the water's edge. Birdwatchers often spot the Malagasy Kingfisher and the Malagasy Pond Heron, both of which are regional specialties. The quiet nature of the crater allows these species to hunt and nest with minimal disturbance. Since the lake lacks a significant fish population due to its volcanic chemistry, the birds here largely feed on insects and small crustaceans that thrive in the shallows.

During the northern hemisphere's winter, the lake attracts various waders and shorebirds looking for a freshwater reprieve from the salty coastal environment. I have noticed that the western edge of the crater provides the best vantage point for photography, as the morning sun illuminates the inner walls without creating harsh reflections on the water. Bring a pair of high-quality binoculars, as many of the smaller endemic species prefer to stay high in the canopy of the surrounding hardwood trees rather than descending to the shore.

Vegetation and Surrounding Flora

The vegetation surrounding the crater is a mix of native tropical forest and small-scale agricultural plots. You will find massive baobab trees scattered across the lower slopes, while the inner rim of the crater is dominated by moisture-loving ferns and mosses. The humidity trapped inside the bowl of the crater creates a microclimate that is noticeably warmer and more stagnant than the coastal breeze found just a few kilometers away. This environment supports various orchid species that are difficult to find on the drier, sun-exposed parts of the island.

Local farmers grow cloves and ylang-ylang in the fertile volcanic soil near the trailheads, filling the air with a heavy, spicy scent during the harvest season. These plantations act as a buffer zone between the human settlements and the protected wetland. While the lake water itself is not suitable for irrigation due to its mineral content, the moisture it provides to the surrounding air benefits the nearby crops. This symbiotic relationship between the village and the lake has existed for generations, though modern conservation efforts now aim to limit the expansion of these farms into the crater itself.

Reaching the Boundouni Crater

Transportation and Trail Logistics

To reach the lake, you must first get to Moheli, which is usually accomplished via a 45-minute flight from Moroni on Grande Comore or a lengthy boat crossing. Once on the island, a shared taxi, known locally as a taxi-brousse, can take you from Fomboni toward the Djando region for about 500 KMF. The drop-off point is near Boundouni village, from where you will need to walk the remaining distance. The trail is roughly one kilometer long and involves a moderate climb that can become exceptionally slippery after the daily afternoon showers.

I recommend hiring a local guide through the Moheli National Park office in Fomboni rather than attempting to find the path alone. The trail is not well-marked and often diverges into private agricultural land where roaming livestock can make navigation confusing. A guide will also be able to point out the specific spots where the sulfur smell is strongest, indicating active volcanic vents beneath the surface. Expect to spend at least 90 minutes for the round-trip walk, not including time spent at the lookout points.

Timing and Seasonal Considerations

The best time to visit is early in the morning, ideally before 08:00, to avoid the midday heat and the frequent cloud cover that rolls in during the afternoon. The light at dawn is particularly soft, making the green hues of the crater walls pop against the dark water. During the rainy season from January to March, the path can become nearly impassable due to deep mud. If you visit during these months, sturdy hiking boots with aggressive tread are mandatory, and a walking stick is highly advised for stability.

Visiting during the drier months of July and August offers the most comfortable temperatures, though the lake level may be slightly lower. Regardless of the season, the humidity remains high, so carrying at least two liters of water is necessary for the hike. There are no vendors or facilities at the lake, so you must bring all supplies from Fomboni. Additionally, the lack of crowds means you will likely have the entire crater to yourself, a rare luxury for any protected natural site in the Indian Ocean.

Frequently Asked Questions

Is there an entrance fee for Dziani Boundouni?

There is no formal ticket booth at the lake itself, but visitors are generally expected to have a Moheli National Park permit, which costs approximately 5,000 KMF. This permit usually covers multiple sites across the island and helps fund local conservation efforts. It is best to purchase this at the park office in Fomboni before heading to the Djando region.

Can visitors swim in the lake?

Swimming is not recommended because the water has a high concentration of sulfur and other minerals that can irritate the skin and eyes. The lake is also home to thick sediment and unknown underwater vents that could pose safety risks. Most visitors find that the view from the crater rim is the primary attraction rather than direct contact with the water.

What should I wear for the hike to the crater?

Wear long trousers and high-traction hiking boots to protect against both the thick mud and aggressive mosquitoes found in the undergrowth. A lightweight, breathable shirt is best for the high humidity, and a rain shell should always be in your pack regardless of the forecast. The trail is often overgrown with sharp grasses, so keeping your legs covered prevents minor scratches.

How far is the lake from Fomboni?

The lake is located about 20 kilometers southeast of Fomboni, which translates to a 30-minute drive followed by a 20-minute walk. Taxis are the only reliable way to cover the distance if you do not have a private rental vehicle. Ensure you arrange a return trip with your driver, as finding a taxi passing by the Boundouni trailhead in the afternoon is difficult.