The Legend of Zelda: a Link to the Past Walkthrough Part 11

Link finds the Magic Hammer.

He fights the first boss of the Dark World: Helmassaur King. Take off his mask with your hammer and dodge his tail's attacks. When the mask brokes, shoot arrows at his head, where lies a green jewel.

Link rescue the first maiden.

ITEMS FOUND:
Magic Hammer
First Crystal
Heart Container