Indian Navy regularly sends adventure expeditions to the Meghalaya caves, but diving in submerged caves is yet to be attempted

by Cmde RS Dhankhar (Retd)

It was the most daring operation in recorded history to rescue 12 boys and their coach stranded in Thailand’s flooded Tham Luang cave complex after 17 days of being underground. It will now become a case study in 21st century globalisation, leadership, crisis management, utilisation of technological resources and human skills coupled with efficient international coordination. It will also serve as a great precedent in the world of rescue operations in caves, mines and other underwater subterranean spaces. This will be something that future divers will study and be sure to learn from.

In India, most caving exercises are centered in Meghalaya. There are more than 1,200 caves and only about 400 of them have been explored. Indian Navy regularly sends adventure expeditions over there, but diving in submerged caves is yet to be attempted. The Marine Commandos and divers of the Indian Navy are qualified to undertake this kind of operation. In the past, the Navy has undertaken diving operations in the flooded Kolkata metro tunnel in 1991, and also some coal mines. However, the capability of cave diving per se does not exist.

The Tham Luang operation can be divided into three phases: search, rescue, and revival.


The search phase lasted from 24 June to 2 July when the young ‘Wild Boars’ soccer team was located four km inside the caves, 800-1,000 meters below the surface of the Doi Nang Non mountains of Chian Rai province in northern Thailand. To facilitate quick search and rescue in the location and with the prevalent monsoon conditions, it was essential that the rising water levels in the caves be controlled, which posed the main threat to the safety of the trapped group.

The advanced technological capability of submersible pumps to de-water the caves came to the rescue and neutralised the threat of even more flooding. Round the clock pumping out of the water led to most of the cave length being walkable or at least ensured that the total dive time was reduced drastically. It was reported that nearly 120 million litres of water were pumped out over 75 hours, reducing the water levels by around 40 per cent. The submersible pumps installed deep inside the caves removed an estimated 16,00,000 litres of water per hour.

The Czech Republic and India had offered four of these pumps each, showing how camaraderie comes into play between nations in times of humanitarian crisis. Additionally, drones with powerful zoom cameras and thermal imaging were used to create a 3D image replica of the mountain to ascertain the water flow and divert it away from the caves and the location of the group specifically. The reduced level of water now facilitated the establishment of a support base 1.5 km inside the caves where hundreds of air cylinders and other necessary equipment were transported with the help of wire-pulley systems. Waterproof electric cables and lights were installed for better visibility and power requirements. This support base proved crucial for the search divers and extended their reach inside the caves along with prolonging their dive time and providing the trapped group various essentials and sustenance.


The rescue phase lasted for eight days commencing on 3 July. This posed its own challenges primarily because the oxygen level down in the caves were reduced to 15 per cent as opposed to the normal 20-21 per cent in our atmosphere. The group was weak due to the lack of adequate food, water, and fresh air. To prevent hypoxia setting in, an air supply line was rigged into the chamber by 6 July. In addition to this, the group was supplied with high protein foods, vitalising liquids, necessary painkillers and antibiotics. A medic along with three divers were positioned with the group to boost their morale and teach them basic swimming and diving skills.

Fiber optic cables were laid up till the group so that they could communicate with the outside world, which would ensure that the spirits of the boys and their families outside along with the rest of the world stayed up. Apart from rescue by diving, the options of drilling an escape shaft and also waiting for the rains to subside were kept open and mulled over.

The Thai authorities had the benefit of advice and help from around a hundred diving experts and thousands of support professionals from across the world. Elon Musk of Tesla and Space X fame even left behind a mini-submarine if required. Israeli company Meshtec provided 17 hi-tech walkie-talkies to enable communication between the rescue teams deep within the cave. These sets could relay and broadcast data and video beyond the line of sight. It proved to be very useful and was responsible for the whole world remaining updated about what was happening in the caves.

In keeping with the adage ‘old is gold’, low-frequency radio sets developed 20 years ago in Britain, which could penetrate through hundreds of meters of solid rock were also provided. To overcome the problem of muddy waters and poor visibility, the divers rigged eight mm guidelines and divers were equipped with long endurance underwater flashlights. Navigation of narrow/tiny crevices and passages was made possible by the use of smaller, lightweight carbon fiber air cylinders which could be pressurised beyond 3,000 psi for longer endurance and dive times. The improved full face masks with positive pressure inside ensured easy breathing and zero leakage. This technology coupled with the latest diving suits and flexible stretchers proved useful in sedating the group and avoiding the risk of making them dive and swim. The method of rescue by sedation and carrying of the rescued persons’ air cylinders by the lead diver proved to be the most efficient.


After the rescue, the boys were quarantined in the city hospital to check their vitals and for their recovery to good health. It may still take a week or two before they are fully recuperated.

The Thai cave rescue was a combination of advances in technology, human selfless endeavour, the organising capability of the Thai authorities, and ready support of the locals and the world that won the day against all odds.

The author is the Founding Director of the recently established Kahnoji Angre Maritime Research Institute, Nashik