Proposed transcontinental crossings

The Darién Gap is a remote, roadless, and dangerous area of rainforest on the international border between Colombia and Panama. Stretching across southern Panama's Darién Province and the northern portion of Colombia's Chocó Department, it acts as a natural barrier between North America and South America. Consisting of a large drainage basin, dense rainforest, and mountains, it is known for its remoteness, difficult terrain, and extreme environment, with a reputation as one of the most inhospitable regions in the world. Nevertheless, as the only land bridge between North America and South America, the Darién Gap has historically served as a major route for both humans and wildlife.

project of a railway tunnel between Russia and Alaska

theoretical tunnel that would span the Atlantic Ocean

railway tunnel

proposed structure in the Strait of Tiran