The Victoria Amazonica has been reportedly observed, in one instance, to support a load of 498 pounds.

If you try to pull this sort of thing off, do note that the load has to be evenly distributed across the leaf. And also be spread out enough that it does not punch through, i.e. standing on it on your own two feet would probably be a fraught undertaking. Best to lie on it on your belly. Given that this is endemic to the tropics of South America, I would also recommend you have fun avoiding getting eaten by piranhas and/or giant anacondas while you try it.