Humans have conquered and spread throughout the world, finding a way to live in every climate on Earth. However, there are three places humans have only begun to explore.
Since the beginning, humans have lived and thrived on land. Humans have been atop the highest mountains and settled into the lowest valleys. Wherever the sun touches land, humans have found a way to live.
The Earth is huge. The total surface area is almost 200 million square miles. There are almost 60 million square miles of land. Just beneath the surface of the land is another 60 million square miles of subterranean area.
Imagine if we changed our dwellings to vast underground complexes with spiral stairwells back up to the surface. The dwellings can be large, but take up very little area above ground. Above ground, natural plant and wildlife can be preserved as park and farm land, with surface entrances to the underground and domed skylights to allow natural light below. An underground subway system composed of one-way tracks will form rings to transport people between clustered communities. Each individual underground community will have their own local subway loop and be self-sufficient.
Another 140 million square miles of the Earth is covered by water. It represents another vast frontier that is still mostly unexplored and unconquered.
We are still far from the underwater domed cities shown in science fiction stories. More practically, we could giant floating ocean platforms with communities of people living in the massive pocket of air beneath them. We already have massive cruise ships where people permanently live aboard. The ocean platforms I’m talking about will be so large that they will have false beaches on the outer edges. They will effectively be floating islands.
Since the advent of skyscrapers, air travel, and space exploration, humans have already begun to explore the air. Much has already been written about the possibilities for human expansion into the air.
We can continue building higher buildings where thousands of people can live over a relatively small footprint of land. We can grow vertical gardens to take better advantage of the sunlight.
We can continue to make advances in aircraft, building larger vessels able to stay in the air longer. Perhaps it is possible to build an aircraft that can stay in air indefinitely while being powered by solar or nuclear power.
We can build bigger and better space stations, and perhaps colonize other planets. Maybe we can send our waste to the moon, and bring back precious rare earth metals.
As the human population grows exponentially, it becomes increasingly important to explore the uninhabited frontiers around us. Everybody lives for different reasons. There are those among us who live for bravery and glory. They have fire in their hearts. They are our explorers, marine scientists, and astronauts. They are the common people who work dangerous jobs on the frontiers, mining the earth, sailing the seas, and flying. They are those with the same adventurous spirit as the famed land explorers of the past thousand years.