page_title: Tham Luang cave rescue
section_title: Challenges
hierarchical_section_title: Tham Luang cave rescue / Planning and preparation / Challenges
caption_attribution_description: English: Pumps are used to divert water from lakes that drain the Tham Luang cave, in an effort to reduce water levels in the cave during June–July 2018 rescue operations.
context_page_description: In June and July 2018, a widely publicised cave rescue saved the lives of members of a junior football team who were trapped inside the Tham Luang Nang Non cave in Chiang Rai Province, Thailand. Twelve members of the team, aged eleven to sixteen, and their 25-year-old assistant coach entered the cave on 23 June after football practice. Shortly afterwards, heavy rains partially flooded the cave, blocking their way out.
  Efforts to locate the group were hampered by rising water levels and strong currents, and no contact was made for more than a week. The rescue effort expanded into a massive operation amid intense worldwide public interest involving international rescue teams. On 2 July, after advancing through narrow passages and muddy waters, British divers John Volanthen and Richard Stanton found the group alive on an elevated rock about 4 kilometres from the cave mouth. Rescue organisers discussed various options for extracting the group, including whether to teach them basic diving skills to enable their early rescue, wait until a new entrance was found or drilled, or wait for the floodwaters to subside at the end of the monsoon season months later.
context_section_description: The point where the boys became stranded was about 4 kilometres (2.5 mi) from the entrance and 800–1,000 metres (2,600–3,300 ft) below the top of the mountain. The route to them had several flooded sections, some with strong currents and zero visibility, and some extremely narrow parts, the smallest measuring only 38 by 72 centimetres (15 in × 28 in).
  The journey through the cave to the team took six hours against the current and five hours to exit with the current, even for experienced divers.
  From the outset, rescue workers battled rising water levels. In an effort to de-water the cave, a stone diversion dam was built upstream and systems were installed to pump water out of the cave and divert flows that were entering it. On 4 July, it was estimated that the pumps were removing 1,600,000 l/h (420,000 US gal/h) from the cave, ruining nearby farm fields in the process. For a time, well-meaning volunteers inadvertently pumped water back into the groundwater supply. Helped by a spell of unseasonably dry weather, these efforts reduced water levels by 1.5 centimetres (0.6 in) per hour on 5 July, enabling rescue teams to walk 1.5 kilometres (0.93 mi) into the cave. However, heavy rains  forecast for 8 July were expected  to halt or reverse this process and could even flood the position where the team were trapped.
  On 6 July, the oxygen level in the cave was detected to have dropped, raising fears that the boys might develop hypoxia if they remained for a prolonged time. By 8 July the oxygen level was measured to be 15%; the level needed to maintain normal function for humans is between 19.5% and 23.5%. Thai military engineers attempted to install an air supply line to the boys, but the effort was abandoned as impractical.
caption: Pumps used to drain water from the cave and downstream lakes
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