ถ้ำหลวง · Chiang Rai · June–July 2018
Thirteen people trapped inside a flooded mountain for eighteen days, and how about ten thousand people brought them home. Drawn from the numbers.
ถ้ำหลวง · how the Wild Boars came home
nanobotco.github.io/tham-luang
ดอยนางนอน · Doi Nang Non
Doi Nang Non, the Mountain of the Sleeping Lady, runs along the border with Myanmar above Mae Sai. From the right angle its ridge looks like a woman lying on her back. In the Tai Yai story, a princess fled her father with a commoner she loved; soldiers killed him, she died of grief, her blood became the Mae Sai River and her body the mountain.
The mountain is limestone: rock that rainwater slowly dissolves. Over a very long time the water hollowed out Tham Luang, a cave about 10.3 km long. The mouth is 446 m above the sea; the peak is 1,389 m. In the rainy season the mountain soaks up rain like a sponge and lets it out through the cave. A sign at the mouth warned against going in from July to November. In 2018 the rain came early.
The drawing above is the mountain in profile, made from six bell curves added together, one for each part of the Sleeping Lady. Press play to run the eighteen days.
From the mouth to Nern Nom Sao
Seen from above, the passage runs north from the mouth, west through three big chambers, then south past a T-junction to a sandy bank the rescuers named Pattaya Beach, after the seaside town. The team was on a ledge about 400 m past it: Nern Nom Sao.
Cave divers lay a guideline, a thin rope, as they go, so they can follow it back by touch when they cannot see. John Volanthen ran out of line just short of the team, surfaced, and found them.
How far in? The governor's briefing that night said 4 km from the mouth. Martin Ellis's survey map puts the ledge about 2.6 km in. This trace, a smooth curve through points copied from a public-domain sketch map, measures 2.5 km.
Traced from Per Meistrup's CC0 map of the rescue, checked against Martin Ellis's 2018 survey. Where the water stood changed by the hour; blue sketches the stretches divers had to swim. Tham Luang on Mot Dang
Drawn to scale: 1 cm here is the same size everywhere on the picture. Football size from FIFA's Laws of the Game (68–70 cm round).
38 × 72 cm
The tightest gap on the way out measured 38 by 72 cm. A football, size 5, is about 22 cm across. Three side by side fit through; a fourth does not. Stacked, two do not fit: the gap is less than two balls high.
Each boy wore a full-face mask fed from an oxygen cylinder clipped to his chest. In a squeeze like this the diver pushed him through from behind, keeping his own head higher, so that in the dark his head hit the rock first. He checked the boy was breathing by the bubbles he could see and feel.
A billion litres
The rescue pumped more than a billion litres of water out of the cave and the lakes that drain it: as much as 400 Olympic swimming pools. A stone dam upstream turned streams away; pipes carried the water off, and flooded farmers' fields.
On 4 July the pumps were pulling out 1.6 million litres an hour. Slide to run them: at that rate a billion litres takes 625 hours, 26 days. The rescue did not have 26 days. On 5 July a dry spell let the water drop about 1.5 cm an hour, and the plan had to work before the next rain.
An Olympic pool: 50 × 25 × 2 m = 2.5 million litres. A billion litres ÷ 2.5 million = 400 pools.
21% → 15%
Air is about 21% oxygen. People work normally between 19.5% and 23.5%. By 8 July the air where the team sat measured 15%. Army engineers tried to run an air line in and gave up; it could not be done in time.
Each dot in the jar is one part in a hundred of the air. Slide to watch the oxygen thin. Then count the breathing: a person at rest uses about a quarter of a litre of oxygen a minute. Thirteen people, and from 3 July four rescuers with them, use it up day after day in a pocket of air the mountain had sealed with water.
About 0.25 L of oxygen a minute is a resting adult's use (physiology textbooks). Children use less, so this is a high count. The air figure is the oxygen ÷ 0.21.
Thirteen journeys, three days
The team could not swim the way out awake: some could not swim at all, and panic underwater would kill a boy and his diver. So Dr Richard Harris, an Australian anaesthetist and cave diver, put each boy to sleep with ketamine. Each boy was tied to a lead diver, dressed in a wetsuit and a buoyancy jacket, with a mask over his whole face.
One dose lasted 45 minutes to an hour, and the trip took three hours on the first day, so divers Harris had trained gave top-up injections on the way. The lead divers swam over a kilometre; on dry stretches support divers carried the boy on a stretcher, and the vet Craig Challen checked him before the next dive. From Chamber 3, hundreds of people passed each boy hand to hand, sliding and zip-lining him over the rocks to the mouth.
The boys chose the order themselves: whoever lived furthest away would go first, so they could get home and tell everyone the others were all right. They thought they would be cycling home.
The sleep line is a sketch of 'each dose lasts 45 minutes to an hour', not a measured drug level. Journey times: three hours on the first day, a little over two on the last. Starts are 45 minutes apart, as the divers spaced them; the clock hour of the first start is a sketch.
In the order they came out. Ages at the time. The coach and three of the boys had no nationality; they were made Thai citizens on 26 September 2018.
Day one · 8 July
Day two · 9 July
Day three · 10 July
About ten thousand
About 10,000 people worked on the rescue: some 2,000 soldiers, 900 police, people from about 100 government agencies, more than 100 divers, and volunteers who cooked, cleaned, washed clothes and looked after the families. Ninety divers worked inside the cave, 40 from Thailand and 50 from abroad. Teams came from Australia, Belgium, Britain, Canada, China, Denmark, Finland, Israel, Japan, Laos, Myanmar, the United States, Ukraine and more.
More than 700 air cylinders were used, 500 of them inside the cave at any one time while 200 waited to be refilled. The king later decorated 188 people for the rescue: 114 from abroad and 74 Thais.
One dot, one person. Group sizes are the round numbers the reports give; the rest are everyone else who came.
ผู้ที่จากไป
After the last boy was out, the families, the commanders and thousands of volunteers gathered at the mouth to give thanks and to ask forgiveness of Jao Mae Tham, the goddess of the cave, for the pumps, the ropes and the people.
น.ต. สมาน กุนัน · 1980–2018
A former Navy SEAL, 37, who had left the service in 2006 and worked in security at Suvarnabhumi Airport. He volunteered. On the night of 5 July he dived from Chamber 3 toward the T-junction to leave three air tanks, lost consciousness on the way back, and was pronounced dead about 1 a.m. on 6 July. A bronze statue by Chalermchai Kositpipat, twice life size, stands at the cave with thirteen wild boars at his feet.
ร.ท. เบรุต ปากบารา · died 2019
A Navy SEAL diver in the rescue. He died in December 2019 of a blood infection he caught during the operation.
ดวงเพชร (ดอม) พรหมเทพ · 2005–2023
The team captain, rescued eighth, on day two. He died in England in February 2023, aged 17.
เอริก บราวน์ · died 2026
A Canadian cave diver and instructor. He carried air cylinders and gear through the flooded passages, laid and kept up the guidelines, and spent 63 hours inside the cave over nine days and seven missions. Canada gave him the Medal of Bravery in 2019. Friends and family announced his death, at 44, in late September 2026. The cause has not been made public.
Thirteen wild boars, for the thirteen at Saman Kunan's feet.
Photographs in the public domain, and one of the cave mouth from Mot Dang.
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