The ocean presented early humans with a vast mystery. What worlds and fabulous creatures exist in the deep? Today, our understanding has expanded, but the world's waters still offer us an abundance of mystery and awe. We dream less about mermaid cities and sunken Atlantis and instead imagine underwater metropolises and seafloor colonies.
This zeal was especially strong in the late 1950s and early 1960s, when Jacques Cousteau's Conshelf project and the United States Navy's Sealab saw the dream of undersea living realized. Both programs proved that humans can live and work for an extended time underwater. The test subjects tended underwater gardens, tackled underwater construction projects and lived the life of an aquanaut.
Half a century later, the underwater cities still aren't here. Sure, we have unrealized designs such as Giancarlo Zema's semisubmerged Trilobis 65 dwelling and the proposed underwater Dubai skyscraper Hydropolis, but very few underwater habitats. The bottom line is that while humans can live underwater, it's not an easy or cheap life. It's also not necessary.
Circumstances haven't forced humans to consider underwater living seriously, and when it comes to oceanic exploration, unmanned submersibles and automated seafloor stations offer a better value proposition. The National Science Foundation's Ocean Observatories Initiative, for example, calls for a worldwide network of automated observation stations and autonomous underwater vehicles.