English: This image, acquired by Sentinel-3B on the 28 June 2020, shows the Volga Delta, which forms where the Volga River empties into the northwestern part of the Caspian Sea. When water from the river enters the Volga Delta, Europe’s largest inland river delta, it splits up into more than 1000 waterways. The delta is considered one of the world's most diverse river deltas because of its remarkably complex hydrographic network. It covers the seaward edge, and is composed of extensive areas of open water, numerous islands, reedbeds and other aquatic plants. The site is an important breeding ground for migratory water birds and it is also well known for the large number of sturgeons and other fish species that can be found there. For these reasons, it has been designated as a Wetland of International Importance by the Ramsar Convention on Wetlands. The Sentinel-3 mission is composed of two twin satellites, Sentinel-3A and Sentinel-3B, that allow us to monitor water quality and detect the possible presence of harmful algal blooms with their daily revisit time at a global scale.