The sea floor

A line resting on dark mud

Now we dive back down. In the middle of the Pacific, the sea floor is 4,000 to 6,000 meters below the surface. No sunlight reaches it, and the cable simply lies on the mud. The ship that lays the cable measures the shape of the sea floor first, then sets the cable down around deep trenches and steep mountains.

Why?The deep sea floor is very quiet. Waves and ship anchors cannot reach it, so a cable can last for decades there.

Learn moreUndersea cables around the world break about 200 times a year. About 80% of those breaks happen in shallow water, caused by fishing nets and anchors. Sharks have bitten cables, but that is very rare. When a cable breaks, a repair ship pulls it up and joins the ends back together.

Time

24 ms → 29 ms

Simplified route · light in glass at about 200,000 km per second