Can a Submarine Cross the Pacific Ocean Underwater Through the Earth? No—The Crust Is Solid

Absolutely not. The premise confuses ocean travel with planetary geology.

Why It's Impossible

• Earth's crust is solid rock—30–70 km thick under continents, 5–10 km under oceans. No tunnels, no permeable pathways.
• Submarines operate in water, not rock. They cannot drill, melt, or phase through the mantle.
• Pressure & Temperature: Even the deepest trench (Mariana, 11 km) is only 0.2% of the way through the crust. Mantle temperatures exceed 1,000°C; pressure >1 GPa.

How Submarines Actually Cross the Pacific

• On the surface (transit mode): Faster, recharges batteries/air, standard for long-distance travel.
• Submerged (patrol mode): Nuclear subs can stay submerged for months, but they follow ocean contours—under the water, not through the Earth.
• Under the polar ice cap: Some transit under Arctic ice, but still in the ocean water column.

Subsea Tunnels Are Different

Humans have built tunnels under seabeds (Channel Tunnel, Seikan Tunnel, Øresund), but these are drilled through rock by massive machines, not navigated by submarines.

The Pacific is crossed on or in the water—never through the planet. Geology doesn't offer shortcuts.