Typical submarine cables at at absolute most 24 strands, more commonly 4, 6, 10 or 12 for modern ones. Terrestrial cables can easily be hundreds and that's quite mundane.
The high capacity in submarine fiber is achieved through DWDM and coherent modulation 100Gbps+ transceivers, not massive parallelism in fiber use.
The high capacity in submarine fiber is achieved through DWDM and coherent modulation 100Gbps+ transceivers, not massive parallelism in fiber use.