Mauna Kea State Park is located in the saddle between Mauna Kea and Mauna Loa. It's a great place to stop for a picnic or to spend the night in one of the rustic cabins (last time I did, you had to bring your own bedding). Elevation is around 2000 meters, and it does get cold, especially at night. When exercises are being conducted at nearby Pohakuloa Military Camp, there may also be some loud bangs due to airplanes breaking the sound barrier or artillery practice. All that being said, it's a stark, but beautiful landscape, and you won't see hordes of tourists. It's also a great place for geocachers, as the saddle road has many caches, and several can be found in and around the park.
This particular cache requires a modest hike (about half a mile) down an unpaved road. Other than goats, you are not likely to see anyone. The cache is housed in a S3 1200 watertight container. Original contents include a travel bug, a wooden nickel, a Where's George dollar, and of course a log and pen. Have fun on your hike and enjoy the cool weather and beautiful views!