Marine cable has it rough, fishing gear can accidently snag cable. Sharks chomping on the cable is simply the most amusing hazard reminiscent of Jaws etc. More than 99% of international internet is handled by fiber and most the fiber is marine.
While transmitting information via satellite may seem much easier and more reliable than undersea cables, fiber optic cables deliver information at a much lower cost than our most advanced satellites today. Satellites are limited in net bandwidth to some extent.
The fiber is very thin, it’s the protection and insulation that makes it thick. Typically the cable is made on a ship and then placed into the ocean. The reason for the robust cable is to allow it to be snagged and raised to be spliced etc.
The core of the cable typically may have 2 or 3 bundles of 256 fibers. Transceivers have improved which has increased the net bandwidth. With more and more marine cables installed the cost of internet connections has come down substantially,
Vietnam recently reported some outages and blamed sharks. The underwater trans-Pacific cable that provides Internet to most of Southeast Asia broke, leaving millions with slow or spotty connectivity. The region faces an estimated repair time of up to a month. Most likely the best solution is to install more fiber around southeast Asia and make it a fault tolerant mesh.