Just how tough is this hike? The Kalalau Trail provides the only land access to the state park and traverses through about a mile of elevation gain. The trail is notoriously narrow, with parts measuring mere inches thanks to land giving way. Throughout large swaths of it, you have mountain on one side and sheer drop off to the ocean on the other side. Compound that with the incredibly rocky terrain -- which bring stress to your toes, ankles, knees and thighs -- with stretches of slippery mud, running streams and crumbling cliffs, and it becomes clear this hike isn't for the uninitiated.