The Hau’ula Loop Trail is a 2.5 mile roundtrip hike that begins in the jungle and ascends to a pine-tree forest. It’s really odd to walk on pine needles on a tropical island but the forest is beautiful!
It’s a pretty easy hike despite some moderate elevation gain. If it has rained recently there may be slippery parts but you might also find a few small waterfalls.
Overall, this is an easy, worthwhile hike.