The hau tree is a native hibiscus with a yellow flower that blooms red before it withers and dies; ula is red in Hawaiian, and this area is named after the red hau flower.
The Hauula Loop hike was one of the first paths constructed by Hawaii's early forestry program.
Consequently it is a thoughtfully laid out, contoured trail with inclines and switchbacks.
The guava-lined path leads to vistas that look down into deep, narrow gulches.