Grutas da Moeda was discovered in 1971 by two hunters who were chasing a fox. The animal sought shelter in a blowhole in the middle of the woods, and when the two hunters went into the blowhole they discovered an authentic natural ‘treasure’. Now, the name of this cave in the parish of Sao Mamede is older. Legend has it that one day a wealthy man was robbed near Grutas da Moeda. Due to the turmoil, the man fell into a blowhole taking the bag with all the coins with him, which brought so much envy. However, the coins scattered with the fall, hence the name of the blowhole, and later on, the cave. Nowadays, many tourists throw coins into the cave lakes hoping that their wishes will come true. Grutas da Moeda covers an area of 1148 feet, which may be visited, and are 147 feet deep.