how deep have we dug into the earth
Humans have dug about 12.26 km (7.6 miles) into the Earth at most, which is only around 0.2% of the distance to the planet’s center.
Quick Scoop: How deep have we dug?
- The deepest artificial point is the Kola Superdeep Borehole in northwestern Russia.
- It reached a vertical depth of 12,262 meters (40,230 feet) by 1989 after nearly two decades of drilling.
- For comparison, Earth’s radius is about 6,371 km, so this hole barely scratches the crust—less than one thousandth of the way to the core.
Think of Earth as an apple: the Kola hole doesn’t even get through the “skin.”
What is the deepest hole?
- Record holder: Kola Superdeep Borehole (SG-3), on Russia’s Kola Peninsula.
- Depth: 12.26 km (7.6 miles) true vertical depth.
- Timeline: Drilling began around 1970, passed 7 km after about 5 years, and continued until it was abandoned in 1989 when further progress became impractical.
- Purpose: It was a scientific project to study the continental crust, not a mining or energy well.
Other notable deep holes (like ultra-deep oil and gas wells) reach roughly 9–12 km but still fall in the same overall range, not dramatically deeper.
Why did we stop at ~12 km?
Engineers didn’t stop because we “ran out of drill,” but because the planet pushed back. Key limits:
- Extreme heat: Temperatures at Kola were far hotter than expected—approaching about 180–200 °C at 12 km—making rock behave more like soft, plastic material than solid stone.
- Rock behavior: At those conditions, the rock slowly flows and squeezes the borehole, warping and closing sections and stressing the drill string.
- Equipment failure: Drills and tools were constantly breaking, getting stuck, or deviating from vertical, making further deepening uneconomical and technically risky.
In short, the deeper we go, the more the crust acts like a hot, moving medium rather than a rigid wall, and current technology struggles to keep a narrow hole open in those conditions.
Mines vs boreholes vs nature
Here’s how our deepest man‑made depths compare with natural low points (values approximate):
| Place / Project | Type | Depth below surface |
|---|---|---|
| Kola Superdeep Borehole (Russia) | Scientific borehole | 12,262 m (7.6 mi) | [9][3]
| Deepest oil / gas wells (various) | Energy boreholes | On the order of 12–13 km measured depth, somewhat less vertical depth. | [10][4]
| Deepest mines (e.g., South Africa) | Gold / other mines | Roughly 4 km below surface. | [4]
| Mariana Trench seafloor | Natural ocean trench | ~11 km below sea level (not drilled; a natural low point). | [9]
So how “deep” is that really?
- Earth’s radius: about 6,371 km.
- Kola’s depth: about 12.3 km.
- Fraction: about 0.2% of the way to the center.
From a planetary point of view, all human digging—mines, wells, tunnels—amounts to scratching the thinnest outer rind of the crust, leaving the mantle and core almost entirely explored by indirect methods like seismic waves instead of physical holes.
We’ve dug impressively deep by engineering standards, but in terms of the whole Earth, we’re still just poking pinholes in the surface.
Information gathered from public forums or data available on the internet and portrayed here.