This coloured SPOT satellite image shows the city of Mumbai, built on a group of islands just off the west coast of the Indian mainland. Vegetation is coloured red; note the racecourse on the western side of the city. On the east side of the main island are the rectangular shapes of the harbour. River sediments appear brown-grey, while the white and grey patches are saltpans. With industrial and commercial development, Mumbai has become one of the most densely populated cities in the world.