My buddy was a BUFF pilot in the Gulf War and told me about flying 50’ off the deck to go under the radar... but he didn’t mean a carrier deck! :-)
Back in the early 80's my ship was doing a Med deployment and made a port call in Sicily at the same time my ROTC roommate's P-3 squadron was deployed to Sigonella. He talked me into going out on a hop with him and we spent some time doing some rigging of the merchant ships. They'd fly parallel to the ship and get a count of the masts and kingposts, then cross the stern to get the name and home port. One of them was a Greek tub with a really long name. The pilot crossed the stern but the observer didn't get the entire name, what with it being in the Greek alphabet and all. So the pilot swung by a little closer and lower. No luck. Tried a third time. Still no joy. Finally the pilot said it was his last chance and made a pass and I swear we were looking up at the name on the stern with the wingtip under the overhang. But they did get the name that time. At least, they claimed they did.
When the terrain hugging radar and low flight manuveurs were developed back in the 70s they gave some of us driving out in the Flint Hills of Kansas some startled moments.
I was driving a lonely back country highway in that era when a B-52 suddenly appeared with a BOOM right on top of me and was gone in an instant.
I almost drove off the highway from the shock and I know I felt a displacement shockwave from its passing. I felt it wasn’t but 50 feet above me but I know it must have been somewhat higher.