The Na'Pali coast trail (Kalalau Trail) is the most beautiful coastline I've ever backpacked. It's a ton of up and down, but only 11 miles long. There is a beautiful bluff at 8 mile to camp on, and a secluded beach at the end, with trails leading inland. Best time is winter (drier and less people) but it's always incredible. The trail does get hairy at spots, so take immense caution and don't hike in bad rain if you can help it.

There is guava and passion fruit if you are keen enough to find it, as well as... ummm.. mushrooms, but those are mostly cleaned out by the small population of (nekkid) people who spend most of their year out there.