This review is for the trail leading to the base of the source of the current lava flow - Pu'u O'o crater/vent. It's called Captain's Trail, and it is one of the top adventures detailed in the Big Island Revealed book, as well as the review below in January 2013.
First off, the trail is officially closed by the County/State as stated by a sign at the trailhead. The hike is mostly through rain forest, which is quite pretty, but it goes on and on for almost 4 miles, or 2.5 hours. Despite some muddy conditions, it was fairly flat and not too strenuous. It ends where the forest meets an old lave flow, where you can then see Pu'u O'o before you. Signs stress it is prohibited to continue further, and, taking the author's advice, we did not proceed further, despite the presence of a smaller trail leading to the summit.
The view of Pu'u O'o was not extraordinary, as it looked pretty much like a dirt mound, and the steam from the vent was barely visible, as it is on the other side (the south side). So, we could not see bubbling lava at the crater or flowing lava.
Overall, I do not recommend this hike. The payoff is not worth the long hike and ignoring the trail closure signs. The only other person out there was a hunter chasing wild pigs with his hunting dogs, which was somewhat unnerving as hikers (and it smelled like he was smoking weed too!). If you do decide to go, do make sure to check air quality conditions/forecast to ensure the vent fumes are not blowing in your direction (North).
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