Mauna Kea: Taller Than Everest from Base to Summit

Yes. Mauna Kea (Hawaii) is taller from base to summit than Everest:

• Everest: 8,849 m above sea level.
• Mauna Kea: 4,205 m above sea level + ~6,000 m below sea level (ocean floor) = ~10,205 m (33,480 ft) total height.

However, "unclimbable" is inaccurate — Mauna Kea's summit is accessible by road (observatories) and hiked. Everest is the highest above sea level and the ultimate mountaineering challenge. Mauna Kea is the tallest mountain from base (mostly submarine).