Iriomote is usually a day trip from Ishigaki by ferry. Whereas it is possible to stay longer it is not easy to figure out accomodation. Best and easiest way to see the forest is the boat tiur to the waterfalls. Along the way is a Japanese guide and you can try to follow with English notes but most people got lost really quickly. It is still beautiful on the way. Once you arrive the tour continues as a hike for about 2h which is rather muddy and steep at points. That is why you got boots at the start of the tour. You will be rewarded with great views at the lookout points where you can have a rest. Some people only walked to the first stop and back. The time is a little tight to see both anyway. The guides also did not accompany you as they go back and forth with other guests.

The most sought after sight on the island are the endemic Iriomote cats, a subspecies of leopards only found here. They say the chance to see one is really low. They are protected and the numbers have plummeted before protection but they are still really shy animals.

Highly recommend.