The site lies on the west coast of Madagascar, and consists of the mangrove located south-east of the town of Tambohorano, a portion of the adjacent coastal area, an offshore island (Nosy Vao), and Lakes Mandrozo and Manapape, located respectively 35 km west and 15 km south-east of the town. Lake Manapape (also called Andranovoribe) lies near the village of Andranovao. The mangrove extends south to the mouth of the Manambaho river and north to the north of Tambohorano. It is relatively dense, dominated by Avicennia, and is surrounded by vast coastal mudflats. The lakes are natural, with clear water. Lake Mandrozo is 2–3 m deep, while Lake Manapape is shallower. Seasonal marshes develop on the periphery of Lake Mandrozo when it floods. There are several islets in this lake, the largest of which is in the middle. Marginal vegetation at Lake Manapape includes abundant Cyperus, as well as Mimosa pudica and floating expanses of water-lily Nymphaea and water-hyacinth Eichhornia. Lake Manapape has very good fish-stocks. Both lakes are surrounded by savanna with palms Hyphaene. Nosy Vao is covered in savanna with some palms Hyphaene in the central part of the island; offshore there are coral reefs.
See Box and Tables 2 and 3 for key species. Eighty-two species are known from the site, of which 20 are endemic to Madagascar. A relatively large number of Anas bernieri breed in the Tambohorano mangroves, representing perhaps 10% of the world population. Large and significant numbers of terns (Sterninae) roost on the reefs off Nosy Vao at low tide; most or all seem to be only passing through, before the breeding season.
Most of the communities neighbouring the lakes live by net-fishing, hunting of aquatic birds and rice-growing, which activities represent threats. In addition, the spread of non-native aquatic plants (Eichhornia and Mimosa pudica) threatens to reduce the importance of the site for birds. However, various taboos constitute a partial protection for the site. Fishermen visit Nosy Vao between August and November to fish for sharks, but do not represent a threat to birds.