The treasure of the Knights Templars is a case in point. Not the one they left for Dan Brown to find out; the one they dug out by apparent accident, which we now call money multiplier. I have no idea what name they had for the thing, nor if they were even conscious they got hold of a treasure in the form of actual, physical, solid gold coins. The jungle puzzle that guarded it consisted in smoothly running a consortium spanning the entire rigmarole of intercontinental tourism: from cruising companies to (crucially) currency exchange, via hostelry, private security, health care, corporate accounting and what else; yet (no less crucially) excluding telefax services.
The OoKT is known to have issued promissory notes against deposits in cash minus brokerage fees. Overtly or not, these notes were managed as maturities. If covertly, that is, if no maturity date was mentioned on the note, one would be implied if they were only payable in a designated town: the implicit date being set by the duration of the physical trip the note had to live thru, to reach its point of payment. Hence the importance of barring the average pilgrim or colonist access to telefax.
The consequence is, the OoKT must have soon noticed each of its exchange offices was squatting on a heap of gold of roughly constant thickness and computed that, at whatever office it showed an inclination to dwindle, this would be linked with an increased popularity of the town among tourists. Hence, the dwindling could be controlled by writing an explicit maturity date on the notes; e. g. under the pretext that secure gold transfer to that specific office is slower if every ship heading to it is full to the rim with passengers of unknown probity.
The next thing any banker in the OoKT's shoes would take notice of is, if each and every gold mattress entrusted to them has constant height over time, then gold transfer is not needed at all: so, let it be replaced with that of authenticated balance sheets (those are needed, to beacon the managers of the exchange offices to the path of righteous poverty), which can be secured at much lower cost. The provision for hijacked ships thus dropping by 90%, the banker can now pocket as much of the exchange fees, and make a living of what was originally a minimal indemnity against the risks in his business.
The 3rd thing is to secure said mattresses against robbers, which as any banker will soon reflect, easily obtains by converting them to something several times heavier than a robber; to wit, real estate. This is how bankers discovered again and again that, for better and often for worse, opening credit in excess of one's reserves amounts to creating actual, physical, 79Au money out of nowhere. This, in my view, is also how Philip the Fair discovered to his dismay that the actual, physical, 79Au-based wealth of the Order litterally flew up the chimney when he sent them to the stake.
The OP only requires the jungle puzzle to appear as a deliberate setup authored by whoever buried the treasure, to select the worthy by intellectual challenge. Who did this in the case of the OoKT is anyone's guess; mine is, twas none other than Lil' Geez' o' Nazar'; witness, extant hints to the place of burial, cf. Matt. XIX:21; "go and sell that thou hast, and give to the poor, and thou shalt have treasure in heaven: and come and follow me. " Which the founders of the OoKT diligently did; only they correctly reckoned that once the Kingdom of Heaven tranferred its capital from Beloved City Up There to earthly Jerusalem down here, its central bank would follow suit, and down with it would the promised treasure.