The Stefanos Crater on the island of Nisyros

The largest and most impressive crater on the island of Nisyros is called Stefanos, and it is a major draw for visitors. This breathtaking natural wonder is one of the largest and best-preserved hydrothermal volcanoes in the world, making it a must-see for anyone traveling to the island.

Stefanos crater is ellipsoidal in shape, with its longest axis measuring an impressive 330 meters and its shortest axis 260 meters. The crater walls rise steeply to a height of about 30 meters, creating a dramatic and awe-inspiring landscape. The crater itself is estimated to be between 3,000 and 4,000 years old, formed by a series of explosive eruptions that have shaped the island over millennia.

As you approach Stefanos, the first thing that strikes you is the sheer scale of the crater. The barren, otherworldly landscape inside the caldera contrasts sharply with the lush greenery that surrounds it. The ground within the crater is a patchwork of colors, ranging from bright yellows and oranges to deep reds and browns, all caused by the various minerals deposited by the volcanic activity.

The crater floor is dotted with fumaroles—vents through which steam and volcanic gases escape from the Earth’s interior. As you walk closer, you’ll likely hear the eerie hiss of steam escaping and smell the pungent aroma of sulfur, a reminder that although the volcano is dormant, it is still very much alive. The temperature of the ground can be surprisingly high, and it’s not uncommon to see visitors testing the heat by cautiously touching the surface with their hands or feeling it through their shoes. This heat is a result of the ongoing hydrothermal activity beneath the surface, where water heated by the Earth’s magma chamber creates this steamy spectacle.

Visitors often descend into the crater via a narrow path, providing a unique opportunity to walk across the crater floor itself. Here, you can observe up close the bubbling mud pools and the vivid mineral deposits, all the while surrounded by the towering walls of the crater that give a sense of being in a natural amphitheater. The experience is both humbling and exhilarating, as it offers a rare glimpse into the raw power of nature.

The geological significance of Stefanos goes beyond its visual appeal. It serves as an important site for scientists studying volcanic and geothermal activity, providing valuable insights into the Earth’s inner workings. The crater is part of the broader Nisyros volcanic field, which has been the subject of numerous studies aimed at understanding the dynamics of volcanic islands and the potential hazards they may pose.

For tourists, Stefanos is not just a geological marvel but also a symbol of Nisyros’s rich cultural and natural heritage. The journey to the crater often begins with a bus ride from the island’s main port, Mandraki, through the rugged and scenic interior of Nisyros. The road winds through small villages and offers stunning views of the surrounding landscape, making the trip to Stefanos as memorable as the crater itself.

Visiting Stefanos is a once-in-a-lifetime experience that leaves a lasting impression. Whether you’re a geology enthusiast or simply a curious traveler, standing in the midst of this ancient volcanic crater is a powerful reminder of the Earth’s dynamic forces and the timeless beauty of nature.