When you send a message to a friend far away, it arrives in milliseconds. Most people think satellites do this. But more than 95 percent of international internet traffic travels through cables on the ocean floor. Some cables are 8,000 meters deep. This month, a new underwater cable between Africa and South America started working.
The cable is called SAEx-1. It is about 6,200 kilometers long, connecting Lagos, Nigeria, to Fortaleza, Brazil, with a branch to Cape Town, South Africa. A group of international companies built it in nearly three years at a cost of $900 million. The cable can carry 120 terabits of data per second — enough to stream 30 million high-definition videos at the same time.
Before SAEx-1, internet data between Africa and South America had to travel through Europe or North America. A video call between Lagos and São Paulo needed data to go more than 20,000 kilometers through London or Miami. The new cable cuts this distance by 60 percent. Delays have dropped from about 350 milliseconds to under 130 milliseconds.
An underwater cable is about as thick as a garden hose. Inside, thin glass fibers carry pulses of laser light. Small devices called repeaters are placed every 70 kilometers to keep the signal strong.
For years, Africa's internet connections went through Europe because of old colonial routes. SAEx-1 helps change this. Africa's demand for internet is growing 45 percent every year. Nigeria's tech industry has received over $2 billion in investment since 2020. Brazil also benefits — it is Latin America's largest economy. Fast, reliable internet is important for both regions.