It's the area where you need to blow up the boulders and before the falling molten rocks. You can see through the path, including the hidden alcove that has a small treasure chest.
Can you post a screenshot? Which RDP/gfx plugin are you using? IIRC, z-fighting is very common with the default Glide64 plugin and there's some setting to adjust to deal with it.
It's the area where you need to blow up the boulders and before the falling molten rocks. You can see through the path, including the hidden alcove that has a small treasure chest.