[00:00.54]Measured from the sea floor,
[00:02.37]The wekiu's home is the tallest mountain in the world,
[00:06.52]Sbout a kilometre taller than Everest
[00:09.78]But it won't hold this record forever
[00:12.32]After millions of years of growth,
[00:14.86]This mountain is slowly but surely losing height
[00:18.44]At a rate of 20 centimetres every 100 years
[00:22.75]In fact, it's so massive that it's buckling the sea floor beneath it
[00:26.15]And sinking into the ocean
[00:29.61]Mauna Kea's future can be glimpsed in the Society Islands of French Polynesia
[00:36.14]The peaks of these islands once rose much higher than this from the ocean floor
[00:42.5]It's been almost 2 million years since their volcanoes first broke through the ocean
[00:47.53]But erosion is washing away their volcanic cores
[00:52.26]Now the only growth occurs just below sea level,
[00:55.85]On what was once the mountain's sloping flanks
[00:59.97]In the shallow waters around an island's base,
[01:02.85]Coral reefs rise towards the surface