So, what shouldn't you miss? The pool by the first cave. That's the pool that's the main picture here. You can't miss it. While most walk on the trail through here, walking all the way through the cave itself is amazing. You'll see what we're talking about when you get there. The picture below - you can scramble up those rocks and go all the way through the cave.
What else? When you get near the end of the trail, which goes to the left toward the last cave that so many explore. Look / go down to the right before your ascent up the hill and walk toward the creek and cavern. Here you'll be able to get close both to Eden Falls and the massive cavern next to it. Most don't go in the cavern. When you're on the trail, it looks just like a big overhang. But go inside it and you really get to feel how massive it is. The two pictures below are under the cavern. Most never go over here. It does not hurt to have waterproof boots.
Below is Eden Falls. Just below the cave at the end.
The cave at the end is definitely worth exploring. Now, you must have lights and be prepared to crawl or scramble through a couple tight spots. How to get to the back of the cave that features an amazing waterfall? There is one section you have to crawl on your knees to get to, and most beginners take this. But when you're there, ask others about the passage that's not so obvious to see, but easier to navigate.
Below is the entrance to the cave.
If you're looking for a great hike, we highly recommend this one. Might as well make a day of it and hit one of the other trails in the area - they're everywhere. While you're there, watch for the Elk in the area. They are right at the entrance to the Lost Valley Trail, on the other side of the road.