Earth from space: Crimea's 'putrid sea' creates beautiful rainbow of color but smells like rotten eggs

A deconstructed rainbow of around a dozen multicolor lagoons, collectively known as the "putrid sea," takes center stage in this stunning satellite image captured around a decade ago. The variety of colors — ranging from raspberry, peach and mustard to lime green, beige and brilliant blue — are caused by several factors, including the microorganisms that live within the lagoons.

The lagoons stretch across the Sivash region — a roughly 3,900-square-mile (10,000 square kilometers) area of marshland across the northern Crimean Peninsula between the Black Sea to the west and the Sea of Azov to the east. The latter is separated from the lagoons only by a narrow piece of land known as the Arabat Spit.

The colorful pools are mainly between 2 and 4 feet (0.6 and 1.2 meters) deep, with some deeper pools extending to depths of 10 feet (3 m). They are all hypersaline, meaning that they contain high levels of minerals that make them salty, and have thick layers of silt across their bottoms, which can be up to 16 feet (5 m) thick. The white color surrounding most lagoons in the image is a mix of salt and silt.

The array of colors in the different lakes' waters is partly due to their respective minerals, acidity and inhabiting vegetation. However, the main driver of color is the species of algae that bloom in their waters, according to the U.S. Geological Survey. When the algae bloom in summer, they can give off a pungent, rotten egg-like smell, which has earned the region its foul nickname.

Related: See all the best images of Earth from space

Researchers estimate that there are around 220 million tons (200 million metric tons) of different minerals in the Sivash lagoons. As a result, the region is also home to a large chemical plant, which siphons off some of these minerals to help create useful chemicals, according to NASA's Earth Observatory.

The lagoons contain a range of wildlife and are protected by the International Convention of Wetlands (ICW). The salty shallows are home to a variety of salt-resistant plant species, including sea lavender (Limonium caspium) and saltbush (Atriplex aucheri), and host to up to 1 million water birds that migrate to the area every winter, according to Ramsar which oversees the ICW.

The Sivash region has been part of Ukraine since the dissolution of the Soviet Union. However, it has been under the control of Russia since the country invaded Ukraine in 2022. (Other parts of the Crimean Peninsula were annexed by Russia in 2014.)

But this is not the first time that the Sivash has taken center stage in conflicts within the region.

In November 1920, during the Russian Civil War, the Red Army — the army of the socialist movement headed by Vladimir Lenin — successfully captured the Crimean Peninsula from the White Army — the soldiers loyal to the old Russian empire — after taking down a major stronghold at Perekop, located along the northern edge of the lagoons.

Perekop was key to holding the Crimean Peninsula and had already successfully repelled multiple front-on attacks. In order to finally take the site, the Red Army launched a surprise attack by wading miles through the lagoons in the dead of night and attacking the White Army from behind. The conflict is known as the Siege of Perekop.