There is a old pirate song which regularly reappears in One Piece, known as Binks' Sake.

Gather up all of the crew, it's time to ship out Binks' brew. Sea wind blows, to where, who knows? The waves will be our guide. O'er across the ocean's tide. Rays of sunshine far and wide. Birds they sing, of cheerful things, in circles passing by.

The song has strong ties to the overall themes of One Piece, and a well-known and much upvoted fan theory is that the mysterious One Piece Treasure is in fact somehow the very Sake that the song is about.

Likely it is not just mundane sake, but some sort of magical liquid, bottle, etc. It could perhaps turn out to be something like the Fountain of Youth, or a giant golden sake cup, or a devil fruit that can create infinite sake. Any of these would count, as long as there is some clear tie from Binks' Sake to the One Piece Treasure. It also counts if there are multiple parts of the One Piece treasure, and only part of it is Binks' Sake.

Oda could do a lot of weird things here, and this is about the spirit of the theory and not the letter.

This market remains open until the full nature of the One Piece is known. If the theory is validated, this market resolves YES. Otherwise, it resolves NO.

I will not trade on this question, so as to keep myself unbiased.

Gather up all of the crew, it’s time to ship out Binks’ brew. Sing a song, and play along for all the oceans wide. After all is said and done, you'll end up a skeleton, so spread your tale from dawn 'til dusk upon these foamy seas.