What about cargo torpedoes? I imagine you could fit an airplane load into a very large submarine/torpedo and send it at 200 km/h with a nuclear powered propulsion.
No idea if this idea is any good or not, but I wouldn’t recommend marketing this solution using the words “nuclear” and “torpedo”.
The fastest submarine of all time only went 75 km/h...
So? The idea is batshit insane, but I'm not sure it's against physics. Imagine a supercavity nuclear powered submarine cargo ship. I can't run the calculations for that. It would probably kill/scare all whales left in the ocean, but it might "work".