As an adult, go to Goron City. Then you will see a little goron rolling. When he is rolling, bomb him (once). Go up to him and talk to him and he will give you the Goron Tunic (It lets you survive in heatness). Then, goto Death Mountain Crater (Top of Death Mountain Trail). You will see sheik. She will give u the Boleoro of fire (It's hard to remember but you'll get used to it).