Here is an animated map from Business Insider that shows all the Undersea Cables that power the global internet
It is more than 150 years since first undersea cable was laid
Map shows all the 300 cables stretching 8.8 Kilometres or 550,000 miles, equivalent distance of circling Earth 22 times that transmit 99% of total internet traffic on the Globe
Longest cable being 38,624 Kilometres or 24,000 miles from Germany to Korea with 39 landing points
Watch how these cables are laid in below video
Below video shows how are these cables are repaired