smartsciencefacts on Instagram: "Underwater construction means building something below the surface of water, like in seas, rivers, or oceans. It is used to build bridges, tunnels, ports, oil platforms, and more. First, workers study the water and land below it. Then, they bring big machines on boats or floating platforms. To start building, they use metal pipes or walls called cofferdams or caissons. These create dry space by pushing water out. Next, they send divers or underwater robots to che