File photo. Photograph:( Reuters )
A large international operation deployed to look for the 12 boys and their football coach in a flooded Thai cave recounted the 'labyrinth' layout of the cave during the ninth day of the search.
The divers from a Thai navy SEAL unit were within 500 meters of a chamber containing an elevated rock mound, nicknamed "Pattaya Beach" by cavers, which could have provided the boys with a refuge when rains flooded the cave, blocking the way out.
Progress has been slow as divers need to widen parts of a narrow 100 meter stretch that they were unable to pass through without their air cylinders becoming jammed.
Bad weather has hampered the rescue effort for the youngsters, aged between 11 and 16, and their 25-year-old coach through the snaking Tham Luang cave -- one of Thailand's longest, and toughest to explore.
Rains finally eased over the weekend and water pumps working around the clock have helped to stem the floods.
But several tunnels leading to where the boys are believed to be were still submerged in murky waters on Monday afternoon as the search entered its ninth day.
The cave is one of Thailand's longest -- it stretches 10 kilometres (six miles) underground -- and also one of the most notoriously difficult to navigate.
A sign outside the cave warns visitors not to enter in the rainy months from July to November.
Its up-and-down tunnels provide plenty of low points for floodwaters to pool, and its claustrophobic passageways are almost impossible to find once submerged.