[frakr]

At the bottom of a lake? Could drive to where you put the boat in. Can't walk to the bottom of a lake.

[weaksauce]

also said it was wet and exposed to wildfire so I doubt it's at the bottom of a lake unless the lake is seasonal.

[olalonde]

If he is into mysteries, he might have picked the riverbank where D.B. Cooper's ransom cash was discovered in 1978 (https://en.wikipedia.org/wiki/D._B._Cooper#Physical_evidence).

[RugnirViking]

If he is into mysteries, its entirely possible that he didn't hide any money and is hoping people will find my cooper or his money instead :)