Nosy Hara

Nosy Hara Marine National Park encompasses an archipelago of small limestone islands and surrounding marine habitats in Diana Region off the northwestern tip of Madagascar, near the town of Ambilobe. The park protects limestone tsingy islands, coral reefs, mangroves, and open ocean habitats in the Mozambique Channel. Among its conservation priorities is the Coelacanth (Latimeria chalumnae)—an ancient fish unchanged for 400 million years—which inhabits deep underwater caves around the islands.

The park's most celebrated species is the coelacanth, which inhabits submarine cave systems in the deeper waters around the limestone islands. The coral reefs support diverse tropical fish, sea turtles (hawksbill and green), and reef sharks. Humpback whales pass through the park's waters on their migration route. Dugong inhabit the seagrass beds. The island vegetation supports colonies of seabirds. Terrestrial fauna on the larger islands includes reptiles and bats. The dry deciduous forest remnants on the islands shelter Ankarana-type fauna.

The limestone islands support dry deciduous forest vegetation similar to Ankarana and Bemaraha, with tsingy pinnacles colonised by succulent Euphorbia, Pachypodium, and Adenia species. The island interiors have dense dry deciduous forest with Commiphora and Dalbergia species. Mangrove forests fringe the sheltered bays and channels, providing nursery habitat for reef fish. Seagrass beds in shallower waters are critical dugong feeding habitat. The coral reefs around the islands have high cover and diversity in protected areas.

The Nosy Hara archipelago consists of uplifted Jurassic limestone islands—part of the same geological formation as the Ankarana and Bemaraha tsingy—that have been sculpted by dissolution into characteristic sharp pinnacles and caverns. The submarine caves around the islands were formed when the limestone was above sea level and subsequently submerged by rising sea levels. These caves provide the specific habitat conditions (cool, dark, deep water) required by coelacanths. The surrounding shallow shelf consists of carbonate sands and reef structures.

The far northwestern tip of Madagascar has a pronounced dry season from May to October, with very little rain and constant trade winds. The wet season from November to April brings cyclone risk and significant rainfall. Sea conditions in the channel are generally calmer in the dry season. Water temperatures around the islands range from 25°C at the surface to below 18°C at coelacanth depths. The combination of warm surface waters and cool submarine conditions is important for the deep-sea biodiversity.

The Antakarana people have inhabited the coastal zone of the Diana Region for centuries, practicing fishing and trading in the Mozambique Channel. The waters around Nosy Hara have historically been important fishing grounds. Coelacanths were known to local fishermen—occasionally caught as bycatch in deep-set lines—before their official scientific 'discovery' near the Comoros in 1938. Traditional fisheries knowledge was critical to locating the Malagasy coelacanth population in the 1990s.

Nosy Hara was established as a marine national park in 2007, following surveys that confirmed significant coelacanth populations in its submarine caves—the third known population worldwide after the Comoros and Sulawesi. The park's creation was driven by the need to protect this extraordinary living fossil and associated marine biodiversity. The park represents a new model of marine conservation in Madagascar, integrating management of terrestrial island and marine components. Conservation partnerships include the African Coelacanth Ecosystem Programme.

Scuba diving and snorkelling on the coral reefs around the islands is the primary visitor activity, with exceptional reef fish diversity and occasional encounters with sharks and rays. Coelacanth watching is theoretically possible via submersible or deep technical diving, though the animals are very rarely seen. Boat excursions visit the limestone islands and their tsingy formations. Birdwatching on the islands' seabird colonies. The park is usually visited from Ambilobe or Antsiranana as part of a northern Madagascar itinerary.

There are no visitor facilities on the islands themselves. Visitors access the park by boat from Ambilobe (approximately 30 kilometres) or from Antsiranana (approximately 100 kilometres). Dive operators in Antsiranana can arrange excursions to the park. Accommodation is in Ambilobe or Antsiranana. The best conditions for diving are from April to October when seas are calmer and visibility is good. Research permits are required for coelacanth diving.

The main threats to Nosy Hara are destructive fishing practices (dynamite fishing and drag nets that damage reefs), collection of sea cucumbers and other invertebrates, and the potential impact of deep-set fishing lines on coelacanths. The park's marine patrol capacity is limited. Community fishing agreements with local villages around Ambilobe aim to designate no-take zones for reef regeneration. The coelacanth population requires long-term monitoring to assess its health. Climate change poses a threat to coral reefs through bleaching events associated with rising sea temperatures.