The Kahanu Garden is located on 'Ula'ino Road, are about a half-mile beyond mile marker 31 makai on the Hana Highway. Just after a mile, the road gives way to broken pavement and the first stream ford. Beyond the ford, to the right, you'll find the entrance to Kahanu Garden, an extension of the National Tropical Botanical Garden.
If the ford has water flowing through it above the poll-markers, turn around and do not try and cross the stream. The 122-acre garden is comprised of a variety of rare native Hawaiian plants and several trees introduced by the Polynesians.
The garden also has one of the largest known collections of breadfruit trees. A mile long trail meanders through the garden allowing visitors to be their own tour guide. Beyond the forest edge you'll find the impressive and colossal Pi'ilanihale Heiau.
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The heiau was constructed completely out of lava rock in the 14th century during the reign of the Pi'ilani Dynasty. The stone platform is the size of two football fields. Visitors are not allowed on the heiau, so you'll have to view it from afar. The coastal views here are beautiful. The last time we checked, the garden is open Monday - Friday, 10 a.m. - 2 p.m. Admission is $10 for adults and free for children. It closes without notice, so don't be surprised if you find Closed signs.