Why can underwater construction with large blocks require divers?

In the context of civil engineering for harbors and sea works, underwater construction involving large blocks or structures often requires divers to perform precise tasks that cannot be handled by surface machinery alone.

Divers are essential for:

• Positioning and Assembly: When structures like gates are installed, divers are required to guide and step them into their final positions after initial placement.1
• Site Preparation and Inspection: In areas where water clarity permits, divers facilitate operations by inspecting the seabed or ensuring that prefabricated elements, such as concrete or masonry blocks, are correctly aligned on a prepared foundation.2
• Sealing and Finishing: Divers may be involved in the final stages of underwater assembly, such as ensuring that joints between large components are properly sealed or that structural elements are correctly secured.1

While some construction can be managed by floating and sinking caissons into place, the specialized skills of divers remain critical for the accuracy and stability of complex marine infrastructure.21