North of Waimea in Kokee State Park on Kauai, the trail to the summit of Mount Wai ale ale, the wettest place on Earth, is an arduous route to be under taken only by the foolish. It is a 17.4 mile route from the main highway through mud bog and swamps to the summit. Most of the trail through the Alakai Swamp does not exist any more due to lack of use and regrowth.
The starting point for the route is about 2.4 miles south of the end of SR550. It begins by leaving SR550 and following the very, very, very rough muddy and pot-holed Camp 10 - Mohihi Road for 5.4 miles to Camp 10. This road is not maintained. A majority of this route will most likely not be passible by car.
Past Camp 10, the route is definitely trail and definitely is not maintained. Matter-of-fact, it is rarely used. After Camp 10, the trail passes through the Alakai Swamp, which is the old caldera of the volcano. The trail through the swamp can be very difficult to follow, maybe even impossible. The weather is almost always rainy with dense fog (clouds). Through the swamp, you can expect to find thigh deep mud. Seriously! From Camp 10 to the Wai Ale Ale summit, it is about a 12 mile hiking trek.
Pretty much anyone you talk to will try to discourage you from attempting this trek. It is difficult and there is a high probabilty that you will get lost and not be able to make the summit.
Overall, Waialeale Summit Trail is the 33rd most popular hiking trail of all 45 hikes in Hawaii.