As its name indicates, it was the third island of the Azores Archipelago to be discovered, after Santa Maria and São Miguel.

Terceira Island is approximately 29 km long and 18 km wide, measuring its perimeter 90 km and has an area of ​​402.2 km2. The highest point on the island is at an altitude of 1022 m and is located in the Serra de Santa Bárbara, on the West side.

The geomorphology of the island means that it presents very varied and beautiful landscapes, which are divided between plains such as Achada, and mountains such as Santa Bárbara. Also noteworthy are some natural accidents such as Caldeira Guilherme Moniz, one of the largest on the island, called Lagoa das Patas or Falca, which together with "Os Viveiros" form a harmonious ensemble, and Chã das Lagoinhas, in the geological reserve of Algar do Carvão. Also noteworthy is the dismantled Complex of Serra do Cume, in the eastern zone, from the top of which Praia da Vitória and Lajes are unveiled. The western part of the island is covered by lush vegetation where the cryptomeria are punctuated. On the north coast, you can see the tip of the "mysteries" and the bathing area of ​​Biscoitos, with traces of volcanic eruptions. Inland, Algar do Carvão and Furnas do Enxofre are worth mentioning.

Its population is 55833 inhabitants. Much of the population has its income from livestock and services.

There is also the Farol da Serreta, and the Serra do Morião or Nasce Água, with its 632 m of maximum altitude, is facing the city of Angra do Heroísmo, it is a singularity in itself. The Pico da Bagacina. Rising from the sea, A Mata da Serreta is a large forest reserve that is home to many species of fauna and flora. Lagoa do Ginjal, which despite its small size has unique plants and protected by law.

Lagoa do Negro, which is located above the Gruta do Natal.

The Facho Viewpoint, in the municipality of Praia da Vitória offers a panoramic view over the city of Praia da Vitória.

Monte Brasil, at the city gates, houses the Fortress of São João Baptista. Jardim Duque da Terceira, almost a botanical garden, has many exotic plants brought from the beginning of maritime adventures. The Ilhéus das Cabras, which offer a nesting place for the various marine species that walk along the coast.

It can also be said that the geomorphology of Terceira has a very rounded shape with a single peninsula that is quite foreshadowed, namely the volcano of Monte Brasil.

It has its highest point in the Serra de Santa Bárbara, which rises to 1021 m, and has an extensive plain that extends from the Serra da Ribeirinha, in the municipality of Angra do Heroísmo, to the Serra do Cume in the municipality of Praia da Victory. According to the Revista de Estudos Açoreanos, Vol. X, Fasc. 1, page. 49, of December 2003.

The geomorphology of Terceira Island is dominated by four large stratovolcanoes and numerous monogenetic volcanic cones implanted in important fractures. From W to E, the following polygenetic volcanic devices are successively listed, truncated by imposing boilers: Serra de Santa Bárbara; the Serra do Morião Massif and the Caldeira Guilherme Moniz Massif; the Pico Alto Massif and the dismantled Serra do Cume Complex, the Serra da Ribeirinha and the Caldeira dos Cinco Picos.

Source: Wikipedia