Take in otherworldly views at the top of the 14,000' dormant volcano. Mauna Kea is also one of the best places for stargazing and astrophotography. You can drive right to the top, but highly suggested you have an SUV; all wheel drive is your safest bet since the last 7 miles to the top are on a very bumpy dirt road.
While you can drive right to the summit of Mauna Kea on the 14 mile access road, the last 7 miles are on a very bumpy dirt road, so make sure your vehicle has plenty of clearance and good tires. All wheel drive will help a lot.
The drive up is amazing itself. Usually there is some fog lingering around a very desolate looking forest area until about half way up, when you reach the visitor information center. After that, the road turns to dirt and the landscape makes a vast change. It looks like another world and the color of the dirt changes to beautiful grays and reds as you ascend.
Once at the top, above all of the fog and clouds, you get to see all of the observatories and an incredible view. There are a few areas you can walk around and hike, but the air is incredibly thin that high up.
Park rangers will ask you to leave as the sun sets and it starts to get dark. They don't want vehicle headlights interfering with the telescopes or the operators. With that said, there are several pullouts along the access road that you can stop at for stargazing.