This is how bridge foundations are built in the middle of the water.
The image shows a cofferdam, a temporary structure used to construct foundations in water. Steel sheets are driven into the ground around the work area to form a barrier that keeps water out.
Next, the water inside is pumped out, leaving the area dry. With the zone cleared, excavation begins until a solid base is reached, and concrete foundations are laid to support the bridge. Once completed, the cofferdam is removed, and the water returns to surround the new bridge foundation.
Credits: Curiosidades••