The Palm Jumeirah is the world's largest man-made island, shaped like a palm tree consisting of a trunk, a crown with 17 fronds, and a surrounding crescent breakwater. Built entirely from sand and rock—no concrete or steel was used for the island's foundation—it added 56 kilometers of coastline to Dubai. To ensure the 'leaves' of the palm were placed with precision, engineers used GPS satellites to guide the dredging ships. One of the biggest challenges was ensuring water circulation; to prevent the water inside the fronds from becoming stagnant, two gaps were cut into the crescent breakwater to allow the tides to naturally flush the system. The island is so large it can be seen from space, and it supports a massive network of luxury hotels, villas, and a monorail system.