Building upon the exploits of legendary explorers is akin to standing on the shoulders of giants. You can reach further than they did, but it doesn't change the fact that they are great. Only by realizing the magnitude of their achievements can those who follow in their footsteps gain the right perspective.

In 1984, over three months of intense exploration, Dr. Bill Stone and a team of divers from the US Deep Caving Team penetrated over 5 kilometers into the Cuerva de la Pena Colorada cave, located in the state of Oaxaca, in the Eastern Sierra Madre mountains. The exploration required overcoming a series of siphons, which are flooded corridors that necessitate the use of diving equipment. Although they were stopped by the technological and logistical limitations of the time, it remains an incredible achievement.

The siphon VII discovered then was considered by Bill Stone to be the most likely connection point to another known immense cave system – Sistema Huautla. Factors supporting this possibility included the large size of the passage and the fact that it heads north, directly towards Huautla.

In 1984, a two-person team managed to dive in siphon VII, penetrating 150 meters and reaching a depth of 55 meters. This was the limit of the technological capabilities of cave diving at the time. As it turned out many years later, further exploration required a large team, CCR rebreathers, and technologically advanced DPV scooters, which were not available during the initial expeditions.

Siphon VII had to wait 34 years, until 2018 when a team of 24 explorers equipped with the latest technical solutions available in cave diving decided to extend the exploration beyond this obstacle and perhaps establish a connection with Sistema Huautla - one of the largest and most iconic cave systems in the world.

Reaching siphon VII alone required a tremendous effort, associated with transporting equipment to a location five kilometers deep into the cave. The team spent many weeks moving all the necessary equipment down, overcoming countless vertical pits and chimneys. Siphon VII is located at the bottom of a huge pit, known as Sherwood Shaft. The water level is 70 meters below the entrance corridor, requiring a descent on a rope and operating from a position attached to a vertical wall descending straight into the water.

Every explorer knows that exploration often leads to disappointment. This was the case here too. Just 20 meters deeper than the point in siphon VII reached by the 1984 expedition, the divers encountered a huge boulder blocking access to further parts of the siphon. Despite intensive attempts to find another route, the team was unable to overcome this obstacle.

However, the divers discovered some clues that shed light on the possibility of connecting the Cueva Peña Colorada cave with Sistema Huautla. The very low flow and fine sediment on the bottom are evidence that the huge amounts of water flowing through the Peña Colorada cave do not come from Sistema Huautla, but probably from the canyon of the same name, located 100 meters above the cave.

During the retreat from the cave, dramatic events occurred - a sudden and incredibly intense influx of water caused by an intense storm front on the surface led to the flooding of the corridors. Six team members were cut off for 69 hours not only from the world but also from their food supplies and bivouac equipment. Fortunately, no one was injured and when the water level finally dropped, everyone emerged to the surface.

Such a sudden rise in water level after surface rainfall is another proof that the cave is fed directly from the surface and it is unlikely to connect with Sistema Huautla.