While welcoming 5.6 million tourists in 2023, the most popular of the Canary Islands, Tenerife, hides a secret deep underground. 

The Cueva del Viento, or “Wind Cave”, is Europe’s longest volcanic tube, which was formed approximately 27,000 years ago during the first eruption of the Pico Viejo volcano near Teide. 

Stretching an impressive 11 miles, it stands as a geological marvel and a testament to the island’s volcanic history. 

It is also the sixth largest lava tube in the world, behind a series in Hawaii. 

The Cueva del Viento takes its name from the air currents that flow through its dark, silent chambers.

It is also considered the most complex volcanic tube in the world, due to its morphology of several levels and passages. It features lateral terraces formed by stabilised lava flows and unique formations such as stalactite-like drops, known as “stafilitos”. 

The underground labyrinth was rediscovered and explored thoroughly in the 1970s, 2,000 years after it was first used by native inhabitants. It contains three different levels of passageways, each full of features such as lava pits and terraces. 

The Cueva del Viento is also rich in fossils of the Canary Island’s large animals, with bones of an extinct species of giant lizard and rat having been discovered here. 

Today, it continues to serve as a vital biological research site, hosting a rich ecosystem over about 190 identified species, most of which are invertebrates. Remarkably, 15 species found within the cave are new to science, including the eyeless cockroach Loboptera subterranea.

Archaeological remains belonging to the Guanches, the ancient Berber native inhabitants of the Canary Islands, have also been found in several entries to the tube system. 

At present, the Cueva del Viento is a tourist attraction on the island offering an unparalleled look into the island’s volcanic origins and unique subterranean life. 

The Kazumura lava tube system, within the 500 year-old 'Ailā'au lava flow of Kīlauea in Hawaii, is more than 40 miles long and is thought to be the longest lava tube cave in the world. 

It was discovered relatively recently, with one of the earliest documentations made in 1966, when one of its entrances was designated as a fallout shelter, designed to protect people after a nuclear explosion.