Aircraft carriers are sitting ducks for countries with real armies. They are an outdated technology in the age of satellites, drones, and guided missiles.
Satellites, drones, and guided missiles all rely on radio emissions for command and guidance. Every ship in the carrier group, plus many dedicated aircraft have SIGINT and ELINT roles specifically dedicated to countering such threats.
While drones and guided missiles do pose a threat to a carrier, the carrier poses a much greater threat to anyone operating such drones and missiles.
Unless you have access to intelligence that you probably shouldn’t be sharing in an Internet forum, neither of us really knows what is needed to guide the missiles of our adversaries.
That said, my day job is a GNC engineer (guidance navigation and controls) for rockets and spacecraft. It’s absolutely possible to hit a carrier with no radio signals whatsoever
I would rule out drones, as yep, if they are radio controlled, you can just blast them with jamming, but guided missiles are absolutely capable of sinking a carrier. The trick is that you need a shitload of them since the carrier group has both long-range missiles and short range CIWS systems to counter those missiles. The only way you can hurt a carrier with them is if you launch a shitton of them.
Or you can actually launch ballistic missiles instead of cruise missiles. The upside is that anti-missile missiles and CIWS are not quick enough to catch them and radars can't really see them if they are not Hamas-style homemade fireworks, but stuff like the Kinzhal. The downside is that it's very hard to guide it in the terminal stage, so they might come very fast, but may be very inaccurate.
If Russia's Kinzhal, or China's DF-ZF is accurate enough to hit a carrier, that's a big problem for the carrier. Whether it is accurate enough is a good question, since maneuvering something that is that fast is not easy, and also if you go that fast in our atmosphere, you are basically blind since the air gets turned into plasma around you (think Space Shuttle reentry). It is a hotly debated topic whether Russia's or China's weapons are accurate enough. OTOH, from the price of a carrier (not including the group or the planes or operation), you can build more than a thousand Kinzhals, so assuming you can launch them all, eventually it might hit something important.
Or you can also just build a diesel electric sub, get some cheap guided torps and torpedo the shit out of the carrier. There is ASW defenses of course, but Sweden has repeatedly demonstrated simulated kills on US carriers with diesel-electric subs.
Stupid actual question: Would a person with a scuba tank and nothing to live for be able to get close to one? I assume there's something looking for people swimming under the water, because if I can think of it, so can an engineer.
On the one hand, a carrier is fricking fast unlike its size would suggest, so good luck catching up. On the other hand, the ASW sonars may not pick up something as small as a diver, but they certainly can fry them.
You're actually totally correct...... for a carrier on its own. But that's why carrier groups exist to defendbthe carrier against things like guided misses and drones.