19.8207°N, 155.4681°W.
Dormant shield volcano on the island of Hawaii, the tallest mountain on Earth measured from base to peak: 10,210 metres total, with 4,205 metres above sea level and the remainder below. Last eruption approximately 4,500 years ago. Sacred to Native Hawaiian religion as the realm of the goddess Poli'ahu and the dwelling place of ancestral deities; the summit was historically reserved for high-ranking ali'i and kahuna. The summit hosts thirteen astronomical observatories operating from 4,200 metres in air with 40% atmospheric water-vapor pressure of sea level — the best optical and infrared observing conditions on Earth. The proposed Thirty Meter Telescope has been blocked since 2019 by Native Hawaiian protests at the access road.
The tallest mountain on Earth stops where its summit becomes a volcano observatory and sacred ground — and the only thing larger than the telescope's mirror is the ongoing argument about whether it should be there.