The closed valleys. The Hana Highway runs along the coast. Behind it, the windward flank of Haleakala is cut by dozens of stream valleys, most of which have no road, no trail and no viewpoint. The Wailua Valley — where our top listing lands — is one of them. You either fly or you do not see them.
The Molokai sea cliffs. Tallest in the world, across the channel, with no coastal road and very limited access on foot. Two listings here cross to them.
The shape of the crater. You can drive to the rim and you can hike the floor, and neither shows you that the basin is the head of two valleys rather than a collapsed chamber. From the air it is obvious in ten seconds.
Notice what is not on that list: waterfalls. They are the thing the photographs sell and they are the weakest argument, because the roadside ones are better from underneath.