Oh, well the Volcano Entrance, I think is right below the warp pad to the Upper Lava side, you have to press the buttons in numerical order

The fish is pretty easy, with Banjo only, you just have to use the Shack Pack (the one that makes you small) and retrieve it from the bottom of the pool and give it to boggy for a Jiggy

the Oil Drill is the Hardest, you might want to check to see if you pressed the button first as I find it kind of hard to Explain in words

Aight..for da fish it just hit me, I already did that one. As for the numerical numbers, I don't remember doing that. So, I'm gonna go try that now.

Thankz, I really appreciate the help. Laterz.

Aight', I've done it, I got one more jiggie. It was one were you have to ride the train, and at the end of the passage the jiggie is above the train.

Now, about entering the volcano. I can't seem to find the one you're talking pressing the numbers in numerical order.

Alright for the volcano, do as I said earlier and use the warp pad at the beginning to warp to the upper lava area, from the upper lava area, step down to find an entryway right below you, keep going forward, and then turn back to enter the volcano, your air supply should now show up on screen, keep advancing and you should eventually come across a switch with an "I" on it (at least its roman numerals in the american version, you might have to use a ground pound on it), it should give you a path to the platform with a "II" on it, then a "III",then "IV" and so on

Found it after typing my post(I just had logged off), thankz anyways. Good lookin' out dogg.