Awesome, impressive series of waterfalls!

"There's a lot of value in having a local guide who can take you to places that aren't on the tourism websites. "

Yes, I agree. Once we tried to explore a secret beach on our own. A trek to the jungle was required to get there while following a Lonely Planet book and crossing the sea during low tide but we didn't find it. We later joined a local tour guide of a maximum of 8 people and found out that the guides are equipped with machetes because the trail had to be cleared first. They are also familiar with the high tide time chart to be able to cross safely.

This part of Croatia is stunning, definitely worth joining a tour group.