A stunning natural phenomenon has thrust Iran’s Hormuz Island into the global spotlight after its coastline turned a dramatic shade of blood-red following intense rainfall. The striking transformation, which saw beaches and shallow coastal waters appear soaked in crimson, quickly went viral, triggering awe, curiosity and concern across social media platforms.
The unusual sight, however, has a perfectly natural scientific explanation rooted in the island’s unique geology. Hormuz Island, located in the Persian Gulf, is rich in iron oxide — particularly hematite — a mineral known for its deep red colour. Geologists explain that when heavy rain falls on the island, water flows through its iron-rich soil and rocks, dissolving and carrying fine iron oxide particles towards the sea.
As these particles reach the shoreline, they stain the sand and mix with shallow seawater, creating the dramatic red hue seen along the coast. The effect is especially vivid in areas where erosion is more pronounced, amplifying the visual impact.
Hematite, the same mineral responsible for Mars’ iconic red surface, oxidises rapidly when exposed to moisture. Hormuz Island — often referred to as the “Rainbow Island of the Persian Gulf” — is already famous for its multicoloured landscape shaped by centuries of geological activity. During periods of rainfall, however, this otherworldly scenery becomes even more striking, resembling scenes from another planet.
While images and videos of the red coastline have sparked comparisons to “blood rain” online, environmental experts have stressed that the phenomenon is entirely natural and harmless. They clarified that the red runoff does not signal pollution or environmental damage but is simply the result of the island’s rare mineral composition interacting with seasonal weather conditions.
Today’s rain on Hormuz Island in southern Iran caused the seawater along the shore to turn red, creating striking scenes. pic.twitter.com/wU4xhZKKOa
— Weather Monitor (@WeatherMonitors) December 16, 2025
Hormuz Island: A Geological Marvel
Hormuz Island is renowned for its vibrant soil colours, which range from red and yellow to orange and purple, making it a popular destination for tourists, photographers and scientists alike. Beyond its visually captivating beaches, the island boasts rugged coastlines, historic sites and a landscape shaped by thousands of years of tectonic and volcanic activity.
The recent red tide has only added to Hormuz Island’s allure, offering a vivid reminder of how weather and geology can combine to create breathtaking natural spectacles. For visitors and researchers, the phenomenon provides a fascinating glimpse into Earth’s dynamic processes — and a rare reminder that nature often produces its most dramatic displays without any human intervention.