<p><strong>Sapphire waters tinged with pink sediment seem to get tangled amid emerald vegetation in a satellite picture of Bombetoka Bay, on the northwestern coast of <a href="http://travel.nationalgeographic.com/travel/countries/madagascar-guide/">Madagascar</a>.</strong></p><p><strong>To celebrate <a href="http://environment.nationalgeographic.com/environment/earth-day">Earth Day</a> National Geographic photo editors selected 20 of the most stunning pictures of Earth, as seen from space, including this jewel-toned shot of the island country off the African coast.</strong></p><p>Captured in 2000 by a NASA satellite, the scene shows where the salty waters of the Mozambique Channel mingle with freshwater outflow from the island's Betsiboka River. Bombetoka Bay is home to some of Madagascar's largest mangrove forests, which provide shelter for diverse mollusks and crustaceans as well as habitat for sea turtles, water birds, and <a href="http://animals.nationalgeographic.com/animals/mammals/dugong/">dugongs</a>.</p><p>(<a href="http://environment.nationalgeographic.com/environment/photos/earth-day-pictures/">This Earth Day, see some of our favorite reader pictures of Earth.</a>)</p>