GEOGRAPHY

The Galapagos Islands consist of 13 main islands, 3 smaller islands, and numerous islets and rock formations. Located about 1000 km off the coast of Ecuador, the islands have a total land area of about 7,880 square kilometers, with Isabella, the largest of the islands, making up about half of the total land area of the Galapagos. The islands are scattered in an area of ocean spanning about 45,000 square kilometers. The highest point on the islands is Volcan Wolf on Isabella Island, at 1707 meters.

Few of the islands are inhabited; the largest human settlement is Puerto Ayora on Santa Cruz Island. Baltra has a military base and civilian airport, San Cristobal includes the town of Puerto Baquerizo Moreno which is the capital of the province, and Isabella’s southern tip holds the third largest settlement on the islands, Puerto Villamil. Few of the islands have a reliable source of fresh water, making human settlement (and life for land mammals) difficult.

All of the islands are of volcanic origin; the region remains one of the most volcanically active areas on earth. The islands are young in geological terms; the oldest of the islands was formed about 5 to 10 million years ago during the Pliocene era. All of the islands are tops of volcanoes which surfaced from under the sea. The youngest of the islands, Fernandina and Isabella, may only be hundreds of thousands of years old. These two islands are still forming through volcanic activity, and may one day form one single island.

The Galapagos islands were probably never connected to the mainland, although there is some speculation that a land bridge once existed connecting the islands to Costa Rica. Some biologists use this theory to help explain how animals originally arrived to the islands, but the theory has not been proven.

CLIMATE

The climate of the Galapagos Islands is mild year round, contrary to what one might expect given the islands location at the equator. There are two main reasons for this. First, the cool Humboldt Current arriving from the south cools the surrounding waters. Second, upwelling, a condition where under certain conditions cool water from deep in the ocean rises to the surface, occurs in the Galapagos. The reasons for upwelling are complex, but the nutrient rich water brought to the surface here is also a key to the remarkable underwater life around the islands.

The terrain of the islands has created local climate zones, including areas that can be very dry or can receive substantial rainfall. The windward sides of the islands (the southeast portions), particularly those with greater variations in altitude, generally receive more rainfall than other areas.

There are two seasons in the Galapagos. From July to December is the dry season, also called the garua season with reference to the drizzle and fog that is common during this period. Contrary to common thinking, this is also the cooler season in Galapagos. From January to June is the warm season, which is also the period with the most rainfall, generally falling in the afternoons. There is a period of transition between seasons where either type of weather can occur. Every few years, an El Niño event occurs, when the water and air temperature can be significantly above normal. Likewise, La Niña events occur, with sea and air temperatures below normal. Both events have a serious impact on Galapagos life; El Niño generally causes high mortality rates for sea life, and La Niña for land animals. These events are part of the balance of life on the islands, and the life here has adapted well to them.

The chart below lists typical average air and water temperatures, along with rainfall, for each month of the year.

Average Ocean and Air Temperatures, Galapagos Islands