It just so happens that I just recently posted about Lower Pua’a Ka’a Fall’s brother, Upper Pua’a Ka’a Falls. So I’m going to direct you there to read more about the Hana Highway.
I will mention a few reasons you might want to visit Lower Pua’a Ka’a Falls. First, you’re in Hawaii, and even the smallest waterfall can be scenic and picturesque! Second, this is an extremely easy-to-visit waterfall. Getting to the Upper Falls requires a little more effort, but this can be viewed quickly after parking. (I don’t remember if it can be seen from the road.) Third, while some of the waterfalls along the Hana Highway are highly visible, it is not always easy to stop. In this case it is. This isn’t a very tall waterfall (at about 15-20′ or so), so some might quickly pass it by, but I think it’s still worth a short stop.
1) Start your journey along the Highway to Hana, heading east along the road toward Hana.
2) Once you’re on the official road, watch the road mile markers. You’ll find the wayside between miles 22 and 23.
3) I don’t remember which side parking was on, but both falls will be on the south side of the road, so head that direction (you’ll be heading upstream). You should see the lower falls very quickly.
Where in the World is Lower Pua’a Ka’a Falls?: map