The forests of Aikawa became an instant gold-rush town. Tunnels multiplied and the population exploded to more than 50,000. Convicts from the island's penal colony flooded the area as cheap labor. Production of gold and silver peaked at nearly 100 tons a year in the early 1600s, providing a crucial flow of funds to the shoguns. Output eventually dropped off and the mines finally closed in 1989.
Kids can go outside to an artificial stream.
The sand is taken from around the island, and park managers put some gold into it to boost visitors' success rate. Those looking for the real thing can venture down a slope to an authentic stream, where it takes about four times as long to panhandle the same amount of gold. Panhandling takes patience and a steady grip. Gold weighs roughly five times as much as sand, so the key is using a combination of swirling and shaking motions to shift all the gold to the bottom of the pan, while using the water to wash away everything else. Don't rush, or all the gold will get thrown out with the sand.