English: The blue waters of the Persian Gulf were colored with swirls of greens and teal in early March 2021. The Moderate Resolution Imaging Spectroradiometer (MODIS) on board NASA’s Aqua satellite acquired a true-color image of the scene on March 7.

Clouds of green swirling near the shore appears to be sediment that has been washed into the water from the land. Sediment can be carried by rain, washed from the shoreline or churned up from the bottom by tides or waves, or blown in by wind. Given the arid climate with nearly sand seas and deserts, at least some of the sediment is likely to have come from dust storms, but the location is suggestive of water action on relatively shallow bottoms.

Along the northern edge of the Persian Gulf, the Shatt al Arab River spills large amounts of sediment into the waters. The sediment appears tan where it is close to the surface. As sediment sinks, the reflectivity changes and it then appears green. As it sinks further, sediment can leave just a faint stain in the waters. All of these color changes are visible from at mouth of the Shatt al Arab and stretch far into the Gulf.

The Persian Gulf is flanked by the Arabian Peninsula with its vast tan, pink and white sand deserts in the south and west, and the dry mountains of Iran in the north. The pinch-point in the east is the Strait of Hormuz, a narrow constriction that connects the Persian Gulf with the Gulf of Oman.