Final answer:
Maunakea is an underwater mountain in the Pacific that is nearly as tall as Mount Everest, forming part of the Hawaiian Islands and created by volcanic eruptions.
Step-by-step explanation:
The underwater mountain in the Pacific which is only 500 feet shorter than Mount Everest is part of the Hawaiian Islands. Specifically, this refers to a mountain called Maunakea, which is a now-dormant volcano.
Maunakea rises 9 kilometers above the ocean floor and forms part of the Hawaiian island chain that was created through volcanic eruptions over time at a hot spot.
This hot spot has produced a chain that is 3500 kilometers long, encompassing many volcanic islands, with Maunakea being one of the most prominent due to its massive size and elevation.