Great hike, but very very challenging. You need to make a reservation online, and kids under 18 are not allowed beyond the tunnel.
The hike is fairly easy up until the tunnel. After that, it becomes more challenging with steep dip offs, and slick rock in some places.
The last third of the hike involves hiking over large stretches of very slick rock, and you'll need upper body strength to hang on to the chains embedded into rocks. For whatever reason, the large rock surfaces are very very slick, and you'll need to go slowly up and down.
The hike was comparable to "Angels Landing" in Zion National Park in the USA, possibly more challenging. It offers a great view, but you'll also get great views from the much easier first third (to the base of the tunnel). If you go -- go early to avoid any crowds read more