In World 1, in the crocodile swamp, there is a hidden door that you
open by horn diving on 2 different targets.  Inside to the left there
are 2 treasure chests. One you ram to open and the second you need a
lock pick to open.  In the one you need the lock pick to open, there
is a dragon egg. Forward there is a spot where you have to do many
glides and avoid swinging hammers, but on the other side there is a
light gem.  On the right, there is a door you can only open you have
electric breath which you get after beating Nasty Norc.  There are 4
machine things you have to zap with your electric breath, you have
about 15 seconds to zap them all.  Then a secret door opens.  On the
other side of that secret door there is an egg thief and many gems.