I report, for information purposes, what little I read to contextualize my visit and try to explain such a concentration of water and water exchanges.
(from Wikipedia)
"[...] The Dead Tombs (also known as Le Formose) are an important hydraulic node located in the municipal area of Genivolta, in the central-northern sector of the province of Cremona.
In a space of a few hundred square meters, three waterways of a certain importance intersect (Naviglio Civico di Cremona, Naviglio Grande Pallavicino and Canale Vacchelli). While the two canals do not exchange their waters except to a minimal extent, the Vacchelli Canal pours almost all of its flow into the Naviglio Pallavicino, the Naviglio Civico and a dozen smaller canals, via a notable system of locks.
Finally, a drainage vessel, built between 1968 and 1981, detaches from the node, which discharges any excess flow of the Naviglio Civico, the Naviglio Pallavicino and the Vacchelli into Oglio.
The reason why so many important watercourses meet precisely in this place is to be found in the morphological characteristics of this strip of the Po Valley. The Crema area is crossed by a relict river valley, called the Morbasco valley or Navigli valley. This valley has its head in the strip of territory between Romanengo and Soncino and can be precisely identified up to a few kilometers south of Soresina. This depression, whose bottom is located about ten meters lower than the fundamental level of the plain, was in ancient times the natural location of a still existing watercourse, the Morbasco, and currently hosts the riverbeds of the Naviglio Civico di Cremona and the Naviglio Grande Pallavicino. At the Dead Tombs there is a narrowing of this valley, which forces the waterways to come closer and then meet, and then separate again as the furrow widens again [...]"