Waterscraper     With only its stabilizing floating ring and transparent dome protruding above the sea, the Waterscraper is envisioned as a tubelike underwater residence and lab—all designed to withstand crushing water pressures.

Natural light would filter down from the dome as the Waterscraper drifts from one destination to the next. Beaches, restaurants, a marina, and a dive center would cater to luxury-apartment dwellers and hotel guests.

Concepts like the Waterscraper are being touted as potential solutions to the planet's urban population pressures.

According to the United Nations Department of Economic and Social Affairs, half of humanity currently calls an urban area home. And before we reach 2050, India's cities will grow by 497 million people, China's by 341 million, Nigeria's by 200 million, and the United States' by 103 million.