I'm at the bat cave with the Waterhouse Leaf Nosed bats. I can't figure out how to enter the cave to explore it. Can someone help me out? I know there's got to be a trick to enter, I just haven't found it yet.

You can enter the cave of the one you need:
- if you have taken the frequency of the emitted cries.
- Read the poster at the resort and know what the bat's frequecy - 16 KmHz.
- Have decoded the rest of the journal and have read this part:
Their gargantuan ears and winged antics provide much needed laughter for my men as the creatures devour the insects attracted to our lantern. The cave which they call home has become a safe haven to us.

Thanks MaG. I guess I forgot to read the journal.

Glad you can move on now.