capital, retains most government offices and is the country's largest city, principal port, and leading commercial centre. Tanzania is a de facto one-party state with the democratic socialist Chama Cha Mapinduzi party in power. Tanzania is mountainous and densely forested in the north-east, where Mount Kilimanjaro is located. Three of Africa's Great Lakes are partly within Tanzania. To the north and west lie Lake Victoria, Africa's largest lake, and Lake Tanganyika, the continent's deepest lake, known for its unique species of fish. To the south lies Lake Malawi. The eastern shore is hot and humid, with the Zanzibar Archipelago just offshore. The Menai Bay Conservation Area is Zanzibar's largest marine protected area. The Kalambo Falls, located on the Kalambo River at the Zambian border, is the second-highest uninterrupted waterfall in Africa. Christianity is the largest religion in Tanzania, but there are also substantial Muslim and animist minorities. Over 100 different languages are spoken in Tanzania, making it the most linguistically diverse country in East Africa. The country does not have a de jure official language, although the national language is Swahili. Swahili is used in parliamentary debate, in the lower courts, and as a medium of instruction in primary school. English is used in foreign trade, in diplomacy, in higher courts, and as a medium of instruction in secondary and higher education; although the Tanzanian government is planning to discontinue English as the primary language of instruction, it will be available as an optional course. Approximately 10% of Tanzanians speak Swahili as a first language, and up to 90% speak it as a second language. Etymology The name "Tanzania" was created as a clipped compound of the names of the two states that unified to create the country: Tanganyika and Zanzibar. It consists of the first three letters of the names of the two states ("Tan" and "Zan") and the suffix, "ia" to form Tanzania. The name "Tanganyika" is derived from the Swahili words tanga ("sail") and nyika ("uninhabited plain", "wilderness"), creating the phrase "sail in the wilderness". It is sometimes understood as a reference to Lake Tanganyika. The name of Zanzibar comes from "zenji", the name for a local people (said to mean "black"), and the Arabic word "barr", which means coast or shore. History Ancient Tanzania is one of the oldest continuously inhabited areas on Earth. Traces of fossil remains of humans and hominids date back to the