Many refer to Mauna Kea as the TALLEST mountain in the world -- others say, "Not so fast."

It all depends on how you define highest. If you measure from sea level, Mauna Kea is not even close.

Mauna Kea extends 13,796 feet into the atmosphere. While Mount Everest extends almost 6 miles into the atmosphere, or to an altitude of 29, 029 feet.

However, if you're measuring from the sea floor, Mauna Kea wins by more than 4,000 feet -- measuring up to 33,500 feet.

So it all depends on how you look at it.