Apparently (and I don’t really have hard sources for this since it’s embarrassing for NATO), in big naval exercises it’s not unusual for run of the mill diesel

Apparently (and I don’t really have hard sources for this since it’s embarrassing for NATO), in big naval exercises it’s not unusual for run of the mill diesel submarines to penetrate the defensive ring around a US carrier group. Stealth is a lot easier in water than it is in the air.