Imagine a summer night on the Atlantic coast. Instead of the usual darkness, the water suddenly flares up with countless blue lights, and each wave that comes ashore leaves behind a phosphorescent trail. This isn’t a special effect from a science fiction movie, but a real natural phenomenon that turns the northern beaches of Spain into the stage for an incredible light show. Locals call it ‘Mar de Ardora’, or the blazing sea, and witnessing it can forever change your perception of the ocean.
The magic is caused by microscopic organisms, mainly dinoflagellates of the species Noctiluca scintillans, which means ‘sea sparkle’. During the day, their clusters may look like oily, orange-tinged patches on the surface, but as night falls, they reveal their secret. Any mechanical disturbance—whether it’s a wave’s impact, a moving boat, or just a hand’s touch—triggers a chemical reaction, emitting a cold blue light. It’s not just beautiful, but functional: the flash of light acts as a defense mechanism, scaring off predators or attracting larger creatures that may drive the attacker away.
While this phenomenon can be observed in various parts of the world, the coast of Galicia—especially the famous ‘Costa da Morte’ and Carnota Beach—is considered one of the best spots for viewing. These areas record the greatest number of such nights in summer. However, neighboring Asturias also has its own secret locations. One of the most well-known is Xivares Beach in the municipality of Carreño. This sandy stretch, popular among surfers and vacationers, takes on a completely different, mysterious atmosphere at dusk.
Xivares Beach, which consists of two parts and stretches for about 800 meters, offers the perfect balance between unspoiled nature and amenities. It’s easy to reach by car—with parking available—or by public transport. But its main treasures are revealed after sunset. To truly enjoy the bioluminescence, visit on warm, moonless nights from June to September. It’s important to avoid using flashlights and phone screens, allowing your eyes to adjust to the darkness. Walk along the water’s edge, run your hand across the wet sand—and you’ll see living lights flicker beneath your feet and fingers.
Hivares holds another intriguing secret. There is a thermal power station nearby, and during low tide, the water near the shore can warm up to unusually high temperatures, sometimes reaching 38°C. This creates a “warm shower” effect in the ocean, which is a rare phenomenon on the Asturian coast. In addition, scenic hiking trails start from the beach, such as the Green Tranqueira Trail, laid along an old railway. It winds through cliffs and coves, offering breathtaking views and a chance to spot fossilized marine life.
This fragile natural marvel is highly vulnerable. Bioluminescent organisms are sensitive to pollution, and even a small amount of litter or chemicals can destroy an entire colony. Artificial lighting also interferes with observation and disrupts natural cycles. So, when heading out to witness the “burning sea,” it’s important to remember your responsibility: leave no trace and treat the ecosystem with care. Only this way can we preserve the magic for future generations, allowing the ocean to keep lighting its mysterious glow along Spain’s coast.
