Naval megaprojects that would remake seas

What planned or conceptual naval infrastructure projects stand out?

Schemes for an inland Australian sea and Atlantropa's Gibraltar dam stand out for their scale and far-reaching maritime consequences.

Extensive Australian planning for an inland sea, described as a Mediterranean within the continent, is one memorable naval infrastructure scheme. The panel also raises Atlantropa, the proposal to dam and turbine the Strait of Gibraltar. Both concepts operate at a scale that would transform coastlines, shipping, power generation, and regional geography rather than merely improve a port. Their appeal here is partly the ambition and partly the enormous consequences that later analysis exposed. These engineering visions would remake the maritime systems around them.