“Only 5% of the ocean has been explored”

Many people believe that humanity has barely begun to understand our planet's vast oceans. This persistent notion stems from the sheer scale of the marine world, which covers over 70% of Earth's surface and extends to incredible depths. It's a natural conclusion given how little of the deep ocean we directly encounter.

Scientifically, this popular perception is largely accurate, especially concerning direct observation. While mapping efforts have progressed, with approximately 27.3% of the global seafloor now mapped using modern high-resolution sonar technology as of June 2025, this differs from physical exploration. High-resolution maps provide general topography, but don't reveal intricate details of marine life or geological features that direct observation does. In fact, explorers have physically seen less than 0.001% of the deep ocean seafloor.

The reason for this limited exploration is multifaceted. The deep ocean presents an incredibly hostile (Review) environment, characterized by immense pressure, freezing temperatures, and complete darkness. Developing and deploying technology to withstand these conditions is both expensive and complex, confining most direct observations to relatively small areas. It's often noted that we have better maps of Mars and Venus than much of our own planet's seabed. Thus, the overwhelming majority of our ocean remains a mysterious frontier.