Mike Munroe, from Melton, has spent more than a decade pawing over battered maps and documents to pinpoint the legendary Treasure of Lima.
Now he believes he has found the "X" marking the desert island spot where the wealth of gold, silver and jewellery was hidden 190 years ago off the coast of Costa Rica.
Funding an expedition to Latin America was always going to be a problem, but Mike has now won support from another amateur treasure hunter called Shaun Whitehead.
Shaun, from Grimston, in the Vale of Belvoir, shares Mike's dreams and has previously won "armchair treasure hunts" – where people follow clues from the comfort of their own homes – including locating a £40,000 gold casket in a national competition.
He might even join Mike on the trip this November.
Mike said: "The treasure was valued at £100 million in 1930 and if it is found the Costa Rican government will get a third share. Another third share goes to the Lima government – as the treasure was stolen – and the other third goes to the salver.
"I am quite confident I can find it."
The treasure was shipped out of the Peruvian capital of Lima during the last days of Spanish control in 1823. The original inventory showed 113 gold religious statues, 200 chests of jewels, 250 swords with jeweled hilts, 150 chalices and hundreds of gold and silver bars.
The Spanish loaded the treasure onto the Mary Dear, under the command of Captain William Thompson, and sent it off to the relative safety of Mexico.
A bishop and several others boarded along with it but Thompson turned pirate and killed them all.
He then sailed to Cocos Island, 350 miles off Costa Rica, where he stashed the haul.
Numerous expeditions have failed to uncover it but Mike believes he knows the whereabouts.
The 54-year-old, who sells his own paintings on Melton market, wants to search 10 sites and has even studied sand and soil conditions.
He said: "We have been given special permission to look for it.
"The official line from the London embassy is 'no more treasure hunts', but this one doesn't involve digging great big holes.
"I will use a special metal detecting mat, like a nylon mesh, which gives a three dimensional scan of the ground.
"If we locate an anomaly under the ground we use a little probe bar to see what it is."
"We have got to work in liaison with the Costa Rican government and as I am an artist I have promised to do six big works for them."
Sponsor Shaun got to know Mike after buying his paintings and was impressed by his research and his permit to explore the island.
Shaun owns a company called Scoutek, which supplies technology such as robots and probes for explorations, and he has agreed to provide equipment as well as £2,500 towards Mike's costs.
He said: "If I can help someone with their life's dream I am prepared to risk a little bit of money, especially because he is doing it in an environmentally friendly way."