Koko Head is a 1000-step path that follows the old railway up to a set of pillboxes built during WWII.  It's a trail not meant for the faint of heart, and I'll admit the steep elevation change left us all flushed and breathless.  We had to watch our step, especially on that slippery day, and occasionally we were on hands and knees to ensure our own safety. But once we finally got to the top, we were astounded by a 360 degree view of Oahu.  On one side was the city bordered by lush green, and on the other was the endless blue Pacific.