Closest I have noticed:
In one episode they actually found the Nuestra Señora de las Mercedes (Our Lady of Mercy), a Spanish frigate and treasure ship that sunk in 1804.
Unfortunately, for the stars of the show, the Odyssey Marine Exploration group; they lost the ensuing case for the rights to the estimated $500 million booty, all the treasure did go to Spanish government.
The lowest points I saw in this kind of documentaries:
The tiny egg cup they found on someone’s British attic allegedly being the Holy Grail (I saw it on German TV, but I think it was a BBC production).
The alleged Veil of Veronica showing Jesus’ real face that looks like a painting of a pre-schooler.
The Perfect Master speaks: https://www.straightdope.com/21342485/did-jesus-have-siblings
In other words, pretty much exactly what I said.
Presumably the ‘Hawkstone Grail’. Its ‘discoverer’, Graham Phillips, has an extensive record of making improbable claims of this sort. He has claimed to have discovered, among other things, the site of Camelot, the identity of Robin Hood and the tombs of King Arthur and the Virgin Mary. His website has this to say -
Critics often wonder how Graham has managed to solve so many historical enigmas. The answer is that he employs a hands-on, investigative approach to his research that gives him a cutting-edge advantage. By collating evidence from many different subject areas, such as archaeology, history and Egyptology, he is able to gain an overall perspective that those tied to a particular discipline are often prevented from doing. More often than not, he has simply applied himself to a mystery that academics have been unwilling, or even afraid to touch.
Well, either that, or it is simply that he is always willing to jump to any conclusion he wants.
Wait! I may have found the Holy Grail. Is it red and made of plastic?
Did it have ping pong balls inside?
Yes, that’s the one I saw. Here’s the “Holy Grail”. Judge for yourself:
Oh, sorry, that’s mine. I was wondering where it had gone…