Deep beneath the oceans lies one of the most crucial — yet least visible — components of modern life: underwater communication cables. Nearly 95% of the world’s international data and voice traffic flows through this vast network of almost one million miles of fiber-optic lines connecting continents.
These cables carry everything from financial transactions and government communications to video calls, cloud services, and AI data transfers. As artificial intelligence grows more data-hungry, investment in subsea infrastructure is accelerating at record speed.
Between 2025 and 2027, global spending on subsea cables is expected to reach $13 billion, nearly double the investment made over the previous three years, according to TeleGeography.
“AI is increasing the need that we have for subsea infrastructure,” said Alex Aime, vice president of network investments at Meta. “Without that connectivity, you just have expensive warehouses.”
Tech giants are now the biggest investors. Meta’s Project Waterworth, a 50,000-kilometer cable linking five continents, will be the longest in the world. Amazon’s Fastnet, connecting the U.S. and Ireland, will deliver speeds equivalent to streaming 12.5 million HD movies simultaneously. Google has funded over 30 subsea systems, while Microsoft has invested in others to bolster its Azure cloud network.
But as global reliance on these cables deepens, so do concerns about security and resilience. Damaged or sabotaged cables can cut off entire nations — as seen when Tonga lost internet access after a volcanic eruption in 2022.
While most damage stems from accidents — fishing nets or dropped anchors — analysts have noted a rise in suspected sabotage near Taiwan and in the Baltic Sea, often coinciding with geopolitical tensions. In response, NATO launched “Baltic Sentry” in early 2025 to protect critical subsea infrastructure.
The U.S. Federal Communications Commission (FCC) has also tightened rules on foreign ownership of cable systems, citing threats from China and Russia. “We’re making it difficult to connect undersea cables directly from the U.S. to adversary nations,” said FCC Chair Brendan Carr.
From the 1850 telegraph line between Dover and Calais to AI-era fiber networks, subsea cables remain the unseen lifeline of global communication — and the quiet battleground of the world’s next digital conflict.