How does an internet message cross an ocean? Follow packets through routers, optical fibers and undersea cables. See how several light channels share a fiber, why bandwidth and latency differ, and how engineers plan, protect and repair the physical connection.
Original animated explanation by Why Unspooled. The route and scale are illustrative; the repair sequence shows a separate hypothetical event with time compressed.
00:00 A message crosses an ocean
00:57 Packets and reliable delivery
02:08 The coast and the optical fiber
03:02 Data and channels of light
04:09 Signal loss, amplification and power
05:05 Bandwidth and latency
06:04 Nearby copies and content delivery
06:55 Protecting the cable
07:15 Planning and laying the route
08:14 When a cable fails
08:51 Backup routes have limits
09:52 Repairing a submarine cable
10:34 The message arrives
Sources and further reading:
Cloudflare: Packets
https://www.cloudflare.com/learning/network-layer/what-is-a-packet/
Cloudflare: TCP/IP
https://www.cloudflare.com/learning/ddos/glossary/tcp-ip/
Corning: How optical fiber works
https://www.corning.com/worldwide/en/innovation/the-glass-age/science-of-glass/how-it-works-optical-fiber.html
Ciena: Wavelength division multiplexing
https://www.ciena.com/insights/what-is/What-Is-WDM.html
NEC: Optical submarine repeaters
https://www.nec.com/en/global/techrep/journal/g10/n01/pdf/100104.pdf
Cloudflare: Latency
https://www.cloudflare.com/learning/performance/glossary/what-is-latency/
Cloudflare: Content delivery networks
https://www.cloudflare.com/learning/cdn/what-is-a-cdn/
KIS-ORCA: Cable installation
https://kis-orca.org/subsea-cables/installation-procedures-and-methods/
KIS-ORCA: Cable maintenance and repair
https://kis-orca.org/subsea-cables/maintenance-repair-operations/
Small questions. Big explanations.
