Towards the western, most volcanically new, edge of the Galápagos archipelago lies the island of Isabela with its five active volcanoes. The massive Volcán Sierra Negra is close to the coastal settlement of Puerto Villamil, from where it can be accessed by bumpy road to the village of San Tomás and then by hiking or on horseback. It is easy to find a guide or join a tour group in Puerto Villamil, but many tourists make their arrangements in Puerta Ayora on neighbouring Santa Cruz.
Riding to the Crater
Horseback tours are very popular and follow tracks worn through degraded pastures dotted with introduced guava trees. The first glimpse of the crater is breathtaking for its sheer size (10 km diameter), viewed from the steep drop-off at the rim. Black boulder fields scarred by erosion channels extend into the distance and tiny plumes of gas evidence recent volcanic activity.
Recent Eruption
The October 2005 eruption was reported by the Ecuadorian Geophysical Institute. A grey mushroom-shaped cloud of gas 20 km high could be observed from the neighbouring island of Santa Cruz. The eruption was concentrated on the northern border of the crater, with lava expelled from three or four main vents. Blocks of igneous material thrown high in the air made up a spectacular fountain with activity concentrated in a fissure running east to west for 2-3 km. Incandescent rivers of lava ran to the south. Fortunately, the depth of the crater meant little danger for the inhabitants of Puerto Villamil.
Other Treks
After the climb to the crater rim, the track continues past dotted clumps of native vegetation - the endemic members of the daisy family - Scalesia and Darwinothamnus - hanging on in the face of grazing animals and competition from introduced plants. It is possible to complete the long trek around the crater's edge, but most visitors swing east to the smaller crater of Volcán Chico. Recent eruptions from this series of scoria cones and other vents took place in 1963 and 1979. During the latter event, the first explosion cued the evacuation of San Tomás and up to 20 vents were active along a 1-2 km fissure. Individual lava fountains reached heights of 100 m and lava flows coalesced to the north, reaching the sea. Today, native vegetation clings to the rocky substrate but close to the vents, lava flows and scree slopes are spectacularly stark and bare in the foreground of panoramic views to the coast and other islands.
