Malpais de Guimar Nature Reserve

Black ʻaʻā lava, broken into sharp clinker, runs from the foot of a volcano straight into the Atlantic, and most of it is less than 10,000 years old. Montaña Grande, the main cone, rises 276 m above the flows. Its crater is about 300 m across and 50 m deep, and it sits lopsided: wider on the leeward side, where the wind pushed the falling ash while the cone was forming. Two older peaks, Montaña de la Mar and Las Morras del Corcho, stand out of the lava plain. Cardón spurge grows from the cracks in clumps of upright stems like organ pipes.

On the shore the sea has worn the flows back since the last eruption, leaving a few beaches and exposed lava tubes. Cueva Honda formed where a large gas bubble swelled inside one of them. Boards along the way explain the landscape in English and Spanish.

• There is no shade on any of the trails, and no toilets or drinking water nearby. Carry all your water and cover up against the sun.
• Wear sturdy closed shoes: every path crosses loose, sharp lava stones.
• The coastal stretch is exposed to the trade wind, which can be strong enough to take a hat.
• The paths are waymarked and easy to follow.
• Dogs are allowed.

The coastal village of Puertito de Güímar sits at the edge of the reserve, and the circuit returns to it. By car, there are two car parks about 320 m and 570 m away in a straight line; from there everything is on foot, over lava stones from the first steps.

By bus, the nearest stops are Puertito de Güímar, about 730 m away, and Finca Don Martín, about 840 m away. The bus also makes a one-way crossing easy: get off at Camino del Socorro, walk through the reserve and take the bus back from Puertito de Güímar.

Best: early morning, from autumn to spring. There is no shade on any trail and the black rock builds up heat as the day goes on; average temperatures run from 17 °C in January to 23 °C in August, with more than 2,500 hours of sunshine a year. The coast faces east, so the morning sun comes up off the sea and lights the cone.

Avoid: the middle of a summer day. Spring days already run hot on the lava, and with no cover anywhere the walk becomes an endurance test in the midday sun.

Malpaís de Güímar is a Special Nature Reserve, and the protection covers the lava itself along with the plants that grow on it. Keep to the waymarked paths: the lava crust and the spurge between them break easily and recover slowly. Leave stones, lava fragments and plants where they are, and do not build cairns or rock stacks.