The secrets in Banjo-kazzoie are the ice key, and all of the mystery eggs. If you collect everything in the original game at the end Mumbo will show you three pictures: a colored egg inside the risen sharkfood island, the ice key in that one level (I don't remember) and another colored egg which i don't remember where. It was discovered that you can get these by using codes on the sandcastle floor in this one level, but I think you can get them without the codes. For example, with the ice key, just outside of the walrus's cave, as I was walking up the snowman's scarf, I noticed a long curved line above the cave. Like in Paper Mario, it looks like it could reveal something. If you don't believe me, look for yourself! I've tried beak bombing it, but it didn't work. Maybe I didn't hit it right. There's got to be something to do with it.

So what do you guys think?