It seems that the vast majority of heiau are close to the ocean, or otherwise more associated with agriculture (mapele) and governance (luakini) and thus in the wao kanaka (realm of people) close to the coast or in the zones of human activity. The Wao Akua (upland realm of the gods), itself sacred, seems not to have been chosen often for siting heiau.
Ka'awako i ka wekiu o Wai'ale'ale (e nana i na pauku ko'a ko luna)
There are some exceptions though, such as the small platform called Ka'awako near the summit of Wai'ale'ale, or the heiau devoted to la'au lapa'au, Keaiwa in the wao nahele (forest zone) of 'Aiea. There is Pu'u o 'Umi, far inland on Moku o Keawe. But these seem the exceptions. What other wahi pana with built sites are you familiar with that are located far from the wao kanaka?