Bahia means bay, which refers to the Bahia de Todos os Santos (Bay of All the Saints) where the capital São Salvador, or just Salvador, is located on a spit of land separating the bay from the Atlantic. It is the largest bay on the Brazilian coast. The state has three different regions, the Atlantic Forest, Recôncavo (Enclosed) with sugar and tobacco cultivation, and the Planalto (plateau), the semi-arid hinterland. A massive geological structure is the Chapada Diamantina (Diamantina Tableland), which divides the state into two distinct geographical zones. Below the tableland to the east the soil is fertile and the rain falls regularly. The tableland itself is part of the Cerrado with tropical savanna, second largest of Brazil's major habitat types, after the Amazonian rainforest. 21 % of the country's land area belong to the Cerrado, particularly in the states of Goiás, Mato Grosso do Sul, Mato Grosso, Tocantins, Maranhão, Minas Gerais.

There are caves all over the state, but most are located in the Chapada Diamantina region. The huge quartzite cave are quite exceptional, there are numerous show caves, but actually the development is rather basi, without trails or light.