Flores Island (Portuguese: Ilha das Flores) is an island of the Western Group (Grupo Ocidental) of the Azores.

It has an area of 143 km2, a population of 3428 inhabitants, and, together with Corvo Island of the western archipelago, lies within the North American Plate. The nearby Monchique Islet is the westernmost point of Portugal.

It has been referred to as the Ilha Amarelo Torrado ('Yellow/Auburn Island') and due to the association with poet Raul Brandão. It is well known for its abundance of flowers, hence its Portuguese name of Flores.

Flores, along with the island of Corvo, is situated on the North American Continental Plate of the Mid-Atlantic Ridge and belongs to the western group of islands in the Azores archipelago. Geomorphologically, the island is composed of two units:

The Central Massif, in the central plain, has many maar structures with lake-filled craters in the adjacent lands;
The Coastal Periphery includes the coastal zones, cliffs, and ancient beaches, as well as the coastal shelf.

The island developed initially from a submarine volcano from the Pleistocene epoch that constructed small calderas and numerous pyroclastic cones. Following a long period of quiescence beginning about 200,000 years ago, several young phreatomagmatic craters and associated lava flows erupted during the Holocene epoch, including two about 3000 years ago. The Funda de Lajes tuff ring, formed about 3150 years ago, accompanied by a lava flow that traveled toward the southeast reach the area of Lajes. The Caldeira Comprida tuff ring in Caldeira Seca (west-central Flores) later, about 2900 years ago, producing a lava flow that traveled towards the region of Fajã Grande.

Azevedo et al. (1986) divides the lavas and deposits into two major volcanic complexes:

The Basal Volcanic Complex, which includes products and deposits of both submarine and subaerial volcanism, formed by pyroclastic deposits and inter-bedded flows of alkali basalts.
The Upper Volcanic Complex represents the main sub-aerial activity composed of three main stratigraphic units, including basaltic to trachytic flows with interbedded pyroclastic deposits in the first two layers, and a more recent unit of exclusively pyroclastic deposits.

During the summer, the island is covered with hydrangeas, which have large blue or pink flowers; this is the origin of the island's name (Flores is the Portuguese word for flowers).

The island has deep valleys and high peaks; Morro Alto is the highest place on the island, reaching an altitude of 914 metres, while Pico da Burrinha, Pico dos Sete Pés and Marcela are other peaks on the island. Flores has several inactive volcanoes; Caldeira Funda last erupted in 1200 BCE, and Caldeira Comprida in 950 BCE. In many situations where water collected in volcanic calderas (or caldeiras in Portuguese), lakes formed: there are seven of these lakes on the island. The Águas Quentes are small hot springs of boiling sulfurous water. The Gruta de Enxaréus is an enormous cavern, about 50 metres long and 25 metres wide.