(260611) -- ISTANBUL, June 11, 2026 (Xinhua) -- An aerial drone photo taken on June 11, 2026 shows the waters at the southern entrance of the Bosphorus Strait near the Sea of Marmara in Istanbul, Trkiye. In recent days, the waters of the Bosphorus Strait in Istanbul, Trkiye, have taken on a turquoise-blue hue. According to Turkish experts, the change in color is a natural phenomenon caused by the combined effects of sunlight, sea currents and plankton. (Xinhua/Liu Lei)