Man's Future Beneath the Sea (1968)
This image from the 1968 book Explorers of the Deep: Man's Future Beneath the Sea depicts the inevitable colonization of the ocean floor.
Man has only two vast, natural frontiers left to him: outer space and the oceans, both of which are still virtually unexplored and unexpoited. In the years to come, technological breakthroughs will make possible a major escalation on the part of the world's oceanographers to develop the resources of the oceans for the benefit of mankind. The new realm of hydrospace will provide thousands of new job opportunities and bring about the birth of dozens of new industries as our oceanic engineers perfect the techniques to dive deeper and stay longer under the surface of the seas.