On Sunday 7th July, a special event took place in the waters facing Monte Isola on Lake Iseo: a technical dive in the cold, green waters with purely exploratory purposes, born from the innate passion and scientific curiosity of Engineer Marco Pilotti.
Marco Pilotti
A professor of hydraulics at the Faculty of Engineering of the University of Brescia, with a profound knowledge and passion for Lake Iseo, he produced a highly detailed bathymetric map of the lakebed. Since then, in every encounter with divers, Marco Pilotti has made sure to mention this extraordinary bathymetric feature of the lake, inviting them to explore it. For this reason, the shallows that a group of divers explored during their recent dive have been affectionately named " Secca di Pilotti ."
In fact, the first person to study the lakebed of Lake Iseo was the engineer Salmoiraghi, who in 1884 decided to conduct a detailed survey of the lakebed, taking 268 depth measurements. To his amazement, upon reaching the center of the lake, west of the island of Loreto, the sounding line, which had stopped at about 240 meters just to the east and west, stopped at just over 80 meters deep. At this point, he actually lost his sounding line, deducing a particularly rugged conformation of the lakebed, or at least of the walls adjacent to the shoal. He had identified one of the most astonishing morphological peculiarities of Lake Iseo.
Over the past 10 years, Marco Pilotti has conducted extensive research on these waters. Among other things, he has built and manages a series of monitoring stations around the lake. His concern is to understand how to halt its degradation, but also to raise awareness of its many fascinating and interesting aspects.
Divers are his allies in this activity, and when the news arrived that they could intervene directly in the water, knowing the exact location of the shoal and being able to explore the still unknown, the organizing machine kicked into action.
Fabio Carrara and Marco Rubagotti, organizers of the event, together with the Submania School and the Hundred Trimix Team Explorer, took care of all the logistics: everything worked perfectly.
The equipment on the comfortable diving boat, which departed from the Riva di Solto headquarters, included everything needed to ensure the divers' safety in the water, and Dario Nicolai and Omar Consonni were simply perfect in managing the operations. While a second motorboat proceeded with the reconnaissance with satellite and depth sounder, the arrival of Engineer Pilotti on a third vessel completed the logistics on the surface.
Diving at the Pilotti reef
Marco Pilotti provided the exact position, the shape of the bottom, its exact depth and the profile astride the reef
The Civil Protection was alerted. The first pair of divers to go into the water and reach a depth of 70 metres at a temperature of 7 degrees were Marco Rubagotti and Fabio Carrara.
Their important task is to bring images of the seabed to the surface in order to provide information and guidance on what was seen. Equipped with powerful illuminators, Rubagotti produced a very interesting video, which is already under examination.
Following in the descent into the water were Ivan Rolli and Carlo Roncoroni, equipped with underwater scooters, with the aim of further broadening the scope of the search, using hypooxygenated mixtures for the reconnaissance on the seabed and hyperoxygenated mixtures for the forced decompression stops prepared by the mixing technician Pietro Bonomi.
Although the bottom was expected to be 70 m but most likely degrading at greater depths, 12+12 bibo loaded with 15/50 were used, a stage with Ean 40 or Ean 50 and pure oxygen for the final decompression stop.
Science and diving
From an initial analysis of the images extracted from the depths, Engineer Pilotti confirms the hypothesis that significant quantities of methane are being released from the seabed, a hypothesis for which he has long sought clear evidence. The seabed appears flat and undulating, characterized by small craters and fissures that are the outlets of the gas, originating from the decomposition of organic matter within the sediments deposited in the lake. The areas of more recent gas emergence are covered by whitish concretions whose nature remains to be clarified. These are extraordinary images, and it is fascinating to think that very few people have likely ever seen the seabed at this point before.
This dive and the resulting video demonstrate what is known as "citizen science," meaning the participation of enthusiasts in surveys that can contribute to the naturalistic and scientific understanding of the environment in which they operate. We hope that this one will be followed by others, and perhaps even stumble upon the lost 19th-century soundings.
