What If Every Ocean Drained? (The Mountain Hiding Under the Sea)

Drain every ocean on Earth and a mountain in Hawaii stands revealed: more than ten kilometres tall from its foot to its summit, while Everest, measured from sea level, is under nine. Which mountain is "the tallest" depends on the ruler, and there are three good ones: height above sea level (Everest), height from its own base (Mauna Kea) and distance from the centre of the Earth (Chimborazo). Then we walk down the drained world: the continental shelves that would add land, the vast abyssal plains, the longest mountain range on Earth under the ocean, canyons and sediment avalanches, the Challenger Deep, why the seafloor is so young, the time the Mediterranean nearly did this, and how little of the seafloor we have actually mapped. Chapters: 0:00 Drain every ocean 0:12 The rules of the experiment 0:44 What does "tall" mean? 2:56 Lower the sea: the shelves 4:08 The abyssal plains 4:25 The mid-ocean ridge 5:20 Seamounts and the Hawaiian chain 5:52 Canyons under the sea 6:28 The trenches 7:09 How young the seafloor is 7:36 When the Mediterranean nearly did this 8:16 The salt 8:44 How much we have mapped 9:28 The ocean is a thin film 9:50 So which mountain is tallest? Sources (every number, with all links, is in the first reply under the pinned comment): Everest 8,848.86 m: 2020 Nepal-China survey, to the snow top (other figures run from 8,844.43 m to 8,850 m): https://nepjol.info/index.php/NJG/art... Base to summit: Mauna Kea about 10.2 km, Denali about 5.5 km, Everest about 4 km (3.7 to 4.7 km depending on where its base is put), USGS: https://www.usgs.gov/faqs/how-big-are... and https://www.usgs.gov/geology-and-ecol... Chimborazo and the geoid, NOAA: https://oceanservice.noaa.gov/facts/h... and https://oceanservice.noaa.gov/facts/g... Ocean depths and shelves: https://oceanservice.noaa.gov/facts/o... ; Harris et al. 2014, Marine Geology 352:4-24 Ridge, seamounts, Hawaiian chain: https://oceanexplorer.noaa.gov/facts/... ; https://oceanexplorer.noaa.gov/facts/... ; https://pubs.usgs.gov/gip/dynamic/Haw... Canyons: MBARI (Monterey), NOAA (Hudson), Talling et al. 2022, Nature Communications 13:4193 Deepest points: Greenaway et al. 2021, https://doi.org/10.1016/j.dsr.2021.10... ; Five Deeps, Bongiovanni et al. 2022 Seafloor age and the Mediterranean: https://sos.noaa.gov/catalog/datasets... ; Garcia-Castellanos et al. 2009, Nature 462:778-781 Salt and mapping: https://www.usgs.gov/water-science-sc... ; Seabed 2030 / IHO: https://iho.int/en/global-seabed-mapp... Map data: NOAA NCEI, ETOPO 2022 Global Relief Model, 60 arc-second, ice-surface elevation (public domain, CC0-1.0), DOI 10.25921/fd45-gt74, https://www.ncei.noaa.gov/products/et... . Equal Earth projection (Savric, Patterson, Jenny 2018); every area figure on the maps is computed from this grid. This is a thought experiment: every ocean and every sea joined to it vanishes (not boiled, not moved), lakes stay, and we skip weather and climate. The maps are real data in an equal-area projection (1.9 km grid cells smooth narrow trenches; floating ice shelves count as land); the cross-sections are schematic. Where sources disagree the video says "about". The Mediterranean refill figures come from a model. The narration is a synthetic (AI) voice. The animation and sound effects were generated by us. Music: "Not Alone" by Lee Rosevere, licensed under Creative Commons Attribution 4.0 (https://creativecommons.org/licenses/...) - source: https://freemusicarchive.org/music/le... "Evening Glow" by Lee Rosevere, licensed under Creative Commons Attribution 4.0 (https://creativecommons.org/licenses/...) - source: https://freemusicarchive.org/music/le... "Countdown" by Alexander Nakarada, CC BY 4.0 (https://creativecommons.org/licenses/..., source https://commons.wikimedia.org/wiki/Fi... "Candlepower" by Chris Zabriskie | From the album Divider | Licensed under Creative Commons Attribution 4.0 | creativecommons.org/licenses/by/4.0/ | chriszabriskie.com The music was edited for this video (shortened or looped, crossfaded, level-adjusted); no other changes.