Iao Needle Ridge seen from the air
Iao Valley (pronounced ee-ow) is located just above the town of Wailuku and is the erosional remnants of a large shield volcano that formed the West Maui Mountains over 1 million years ago.
Iao Needle is actually a basaltic core remnant of the volcano. Mauna Kahalewai (West Maui Mountains) have the second highest rainfall of anywhere in Hawaii at nearly 400 inches per year. The erosional effect of this rain over hundreds of thousands of years created the Iao Needle which is a towering ridge that looks like a free-standing spire. It stands 1200 ft above the valley floor and 2,250 ft above sea level.
These mountains make up the western one-quarter of the island. Called Mauna Kahalewai by ancient Hawaiians (meaning “holding house of water”) this shield volcano last erupted around 320,000 years ago. The highest peak of the Kahalewai, Pu’u Kukui, stands at the back of the valley at 5,788 ft elevation.
It is one of Maui’s most beautiful state parks and a great stop on our Volcanoes of Maui Tour. Walkways, bathrooms, a bridge, remnants of an ancient Hawaiian village and streamside trails are maintained throughout the park.
Wailuku means “waters of destruction” and this seemingly peaceful stream in the valley has been just that. In 2016 floodwaters destroyed portions of the park and damaged many homes in the valley below as well as in the upper parts of the town of Wailuku. It took a year to clean up the debris and build abutments and retaining walls to mitigate future flooding. The park re-opened in 2017 with a new parking area, paths, and stairways.