The hunky Peter Ronson was an Icelandic god....er, uh, athlete who co-starred in 1959's Journey to the Center of the Earth with James Mason and Pat Boone.
His 6'5" tall, blond, muscular, mostly-naked body is really the only reason to watch this awful movie.
He competed in the 110 metre hurdles at the 1960 Summer Olympics in Rome.
I find the film awfully slow. The soundtrack is monotonous, especially during the dimetrodon attack. They take forever to get underground, and most of the "action" is spent spelunking rather than in fantasy worlds beneath the surface. The "magnetic ocean" sequence is given amazingly short shrift, and the buried city set is tiny.