Answer:
About 70 percent
Step-by-step explanation:
Around 70 percent of the planet beneath us is inaccessible by humans. This is because a large and majority part of the planet is covered by water. This include seas, oceans, rivers etc. These are where sea animals thrive and a large amount of ocean floor has been inaccessible by humans.
However due to urbanization a larger portion of the land has been explored and been accessible to humans.