After traversing roughly half a mile up the canyon along the Waimea Canyon Trail, you’ll intersect the Koaiʻe Canyon Trail, a moderate 3-mile (one way) trek that takes you down the south side of the canyon to some swimming holes (avoid them during rainy weather due to the possibility of hazardous flash floods).
This route offers three camps. After the first, Kaluahaʻulu Camp, stay on the eastern bank of the river – do not cross it. Later you’ll come upon the trailhead for the Koaiʻe Canyon Trail (marked by a brown-and-yellow Na Ala Hele sign). Watch for greenery and soil that conceal drop-offs alongside the path.
Next up is Hipalau Camp. Following this, the trail is hard to find. Keep heading north. Do not veer toward the river, but continue ascending at approximately the same point midway between the canyon walls and the river.
Growing steeper, the trail then enters Koaiʻe Canyon, recognizable by the red-rock walls rising to the left. The last camp is Lonomea Camp. Soak up the best views at the emergency helipad before retracing your steps.