In the summer of 1869, Ruffinyi and his friend Gustáv Lang explored a chasm called the “Cold Hole” (Studená diera) at an altitude of 969 m. They threw stones and fired a rifle into the opening — a continuous echo suggested an enormous cavern. On 15 June 1870, Ruffinyi was the first to descend into the chasm on a hemp rope, accompanied by Gustáv Lang, Andrej Mega, and Ferdinand Fehér, with the assistance of miners. They discovered vast chambers covered in ice.

The cave was opened to visitors as early as 1871. As an experienced mining surveyor, Ruffinyi surveyed and mapped the cave in 1873–74 and did much to make it accessible. In 1887 the cave received electric lighting — one of the first caves in the world to do so. Ruffinyi served as director of the municipal mines until his retirement in 1907.