Earth’s tallest mountain, Mauna Kea, ascended for the first time

By Adam Millward

American adventurer – and GWR Hall of Fame inductee – Victor Vescovo first rose, or perhaps that should be descended, to prominence in the record books when he became the first person to visit the oceans' greatest depths in 2018–19. 

But in early 2021, he decided to set his sights higher: namely on our planet’s tallest mountain, Mauna Kea ("White Mountain") in Hawaii. 

If you're wondering why we’re not talking about Mount Everest, it comes down to size vs altitude. Soaring to 8,848.8 m (29,031 ft) above sea level (asl), Everest – aka Chomolungma or Sagarmāthā – is the world's highest mountain. (Incidentally, Vescovo has also climbed that, back in 2012, which makes him the first person to visit Earth’s highest and lowest points, but that's a whole other story.) 

Vescovo waves the Texan flag on the summit of Everest in 2012

The top of Mauna Kea falls far below the lofty zenith of its Himalayan rival, however it is more than a kilometre taller than Everest when comparing the two from base to pinnacle. 

But more than half of this dormant volcano lies unseen underwater. Indeed, of Mauna Kea’s c. 10,211 m (33,500 ft) total height, only 4,207 m (13,802 ft) is above the sea. This makes it half the height of the iconic "8,000ers" – the 14 mountains that stretch in excess of 8,000 m (26,247 ft) asl. 

Avid adventurer Vescovo has also ventured to the North and South Poles (Last Degrees). In 2020, he received the Explorers Club Medal for his contribution to the fields of exploration and science

So, how do you go about tackling a mountain that predominantly lies underwater? Fortunately, when you have one of the world’s most advanced submersibles at your disposal – and a passion for venturing into uncharted waters, both figuratively and literally – a "mere" 6 km (4 mi) of ocean isn't going to come between you and your goal. 

Vescovo told GWR, "I was inspired [to take on this challenge] because it allowed me to combine two of the strongest passions in my life: mountain climbing and ocean exploration."

"I thought it was time for someone to finally ascend the full extent of this massive mountain and, given that I had a submersible capable of going to the base, why not make the attempt? It seems no one climbs mountains and explores the oceans, so I loved the idea of combining the two endeavours." - Victor Vescovo

Vescovo steps off the Limiting Factor sub having completed the first leg of the Mauna Kea journey

In Feb 2021, Vescovo embarked on the first full ascent of Mauna Kea, seeking to traverse it from the seabed to its snow-capped peak over the course of three days. 

He was accompanied on this unprecedented voyage by Hawaiian marine scientist Dr Clifford Kapono (USA), who has lived in the shadow of the White Mountain all his life. 

Mauna Kea is an esteemed, sacred site within Hawaiian culture. It is believed to be the home of deities (Na Akua), and it's said its summit is where the Earth Mother (Papa) meets the Sky Father (Wakea). 

Given its spiritual significance, Vescovo felt duty bound to undertake this journey with a local scientist. "As I have undertaken more than a few scientific expeditions around the world, I have learned that it is very important to involve the local scientific community in what we are doing. 

"These places are, after all, parts of their home – not mine.

"Not only is it courteous, but they can bring a perspective to the mission and the science that we might miss ourselves."

Scaling Mauna Kea presents a host of different terrains, from the depths of the ocean and choppy surface of the sea to alpine slopes and the icy summit

The drastically varied environments and conditions presented by an ascent of Mauna Kea called for both aquatic and terrestrial transportation. 

The epic journey began in the early morning of 1 Feb, when retired US Navy officer Vescovo and Kapono climbed aboard the two-person deep-submergence vehicle Limiting Factor

Piloted by Vescovo, the state-of-the-art sub plunged them to 5,116 m (16,785 ft), where Mauna Kea's flank meets the surrounding seafloor and levels out.

Pillow lava spotted through the sub window on Mauna Kea's submarine base 

While there is no question that Mauna Kea is the tallest mountain, it is worth flagging at this stage that the true "base" (and so also the mountain's precise full height) is contested. It depends on how far from the main island of Hawaii you consider still to be integrally part of the mountain. 

An approximate height of 33,500 ft (10,211 m) has come to be generally recognized, as cited by organizations such as the US Geological Survey. But others put forward slightly more conservative estimates.  

Akin to the start point of an Everest expedition being universally accepted as from Base Camp, which is already 5,364 m (17,598 ft) asl – as opposed to requiring people to walk from sea level, though a few have done that – Guinness World Records deemed the depth of 5,116 m to be a sufficient "starting point" for a Mauna Kea ascent. 

On board the outrigger canoe, coxed by Chad Cabral

The Limiting Factor resurfaced just before midday at which point the voyagers briefly returned to the support vessel, DSSV Pressure Drop, to get changed out of their “flight suits” and into board shorts, before transferring to their next vehicle: a three-person outrigger canoe. 

Under the guidance of experienced local cox Chad Cabral, Vescovo and Kapono rowed 43 km (27 mi) towards Big Island, the largest in the Hawaiian archipelago. After a strenuous five-plus hours of rowing, they pulled gratefully into Wailoa harbour in Hilo, where they walked to their hotel to rest for the night. 

I found the kayaking the most challenging because I have never kayaked – even remotely – such a long distance. I trained as hard as I could for this particular segment, and there were two other expert rowers with me as we did the 27 miles to shore, but goodness, that was a long and tough haul. The weather and waves didn't really help us either – so it was a slog - Victor Vescovo


After a much-needed night’s sleep, day two dawned where Vescovo and Kapono would switch from aquatic to land-based locomotion.

Setting out at approximately 8 a.m., they mounted bicycles and pointed them in the direction of the White Mountain. 

They cycled for 60 km (37 mi), steadily making their way up Mauna Kea’s side, riding as far as roads would allow. 


After making an offering and a prayer to the mountain, as is deemed respectful for anyone climbing Mauna Kea, the pair ventured a little farther on two wheels, before deciding – with 17% gradient slopes ahead – that the bikes had served their purpose. 

They hiked the rest of the way to the Onizuka Visitor Center, located at 2,800 m (9,200 ft) asl, where they would lodge for the night. 

When the mountain became too steep, the pair exchanged pedal power for foot power

On the final day, 3 Feb, Vescovo and Kapono departed on foot at 8.10 a.m. to walk the 9.6-km-long (6-mi) Humu’ula Trail which leads to the mountain’s observatory. 

Once there, in order to reach the actual summit, they had to get out their ski poles to negotiate a super-slippery final stretch of snow and ice. 

Vescovo and Kapono hike on the Humu'ula Trail up to Mauna Kea's observatory

By 1.55 p.m., they were finally standing on the very top of Mauna Kea – 4,207 m (13,802 ft) above the surface of the Pacific Ocean, but crucially more than 9 km (5.6 mi) above their subaquatic starting point where they had began their odyssey. 

Over the course of three days, using a combination of submersible, canoe, bicycle and foot power, Vescovo and Kapono had ascended a vertical elevation of 9,323 m (30,587 ft). That’s the equivalent of almost 30 Eiffel Towers – or about 5% greater than the total sea-to-summit elevation of Everest.

The final leg: Vescovo and Kapono traverse the snow-capped peak of Mauna Kea 

Although Vescovo is a keen mountaineer and has also trekked to the North and South poles, he is best known for exploring the little-known depths of Earth’s oceans. 

Among his many extreme dives, he has made no fewer than 10 descents (as of Mar 2021) to the deepest point of them all – the almost 11-km (6.7-mi) Challenger Deep located in the western Pacific’s Mariana Trench. This represents the most visits to the Challenger Deep by an individual

The trove of data that Vescovo and scientists accompanying him accumulated across the series of dives resulted in a recent revision of the Challenger Deep’s known depth. As detailed in a paper published in the journal Deep-Sea Research in Dec 2021, the lowest point on the planet (in the “Eastern Pool” of the Challenger Deep) is calculated to lie 10,935 m (35,876 ft) beneath the ocean surface, give or take a few metres’ discrepancy. 

Along the way, the many expeditions to the lowest point in the Earth’s crust have resulted in a litany of record-setting milestones, all with Vescovo at the helm of the Limiting Factor

  • First woman to reach the Challenger Deep and first person to visit space and the Challenger Deep: Dr Kathryn Sullivan (USA) on 7 Jun 2020 
  • Oldest person to reach the Challenger Deep: James Wigginton (USA), 71 years 124 days on 26 Jun 2020 
  • First woman to reach Earth’s highest and lowest points: Vanessa O’Brien (UK/USA) on 12 Jun 2020 
  • Longest duration at full ocean depth by a crewed vessel: 4 hr 15 min, by Vescovo, with Hamish Harding (UK) on 5 Mar 2021 
  • Longest distance traversed at full ocean depth by a crewed vessel: 4.634 km (2.88 mi) by Vescovo, with Hamish Harding (UK) on 5 Mar 2021  

Vescovo with Dr Kathy Sullivan, the first woman (and astronaut) to visit the Challenger Deep, in Jun 2020

If all that weren’t enough, this year Vescovo and the Limited Factor also played a crucial role in hunting down the deepest shipwreck

First spotted by an autonomous vehicle in May 2019 near the Philippine island of Samar (although the ship’s identity could not be confirmed at that time), Vescovo launched his own expeditionary mission to the site with maritime historian Parks Stephenson in Mar 2021. 

The bow of the USS Johnston, including its identifying hull number

They were able to locate the unique hull number (DD-557), removing any doubt that this was, as suspected, the USS Johnston – a long-missing destroyer that was sunk in World War II, during the Battle of Leyte Gulf, considered by some as the largest naval battle of all time. 

Over the course of two dives (one with Stephenson and one with sub engineer Shane Eigler), Vescovo and his team were able to calculate its maximum depth to be 6,468.6 m (21,222 ft), for a segment of the vessel's aft section. As well as making the Johnston the deepest shipwreck on record, their intrepid expedition represents the deepest shipwreck dive by a crewed vessel