The evolution of means of transport in the Hundred Islands of lake Saint-Peter has led to the permanent opening of this insular world and to an increased dependency on the surrounding more developed regions. The original means of transports within the islands were primarily developed for the needs of the residents and were therefore in close harmony with the local agricultural activities. The residential areas were, on the one hand, linked to each other by a network of roads and barge crossings and, on the other hand, with the agricultural areas by a complex network of land and water communications. However, in 1938 a network of bridges was constructed linking the northern islands to the left shore of the Saint-Lawrence thus ensuring a better link between Berthier and Sorel ; a new residential axis was thus formed on the islands. While the agricultural activities began dwindiing in the islands, the communication function of the new axis was prospering, this being linked to the remarkable growth of ferry traffic between Sorel and the island of Saint-Ignace. However, this growth was seriously checked, and traffic actually dropped when, in 1967, a new bridge was built across the Saint-Lawrence at Three Rivers and a tunnel was dug under the river, east of Montréal. The construction of another bridge spanning the entire group of islands and facilitating the development of the tourist industry has been considered. This must be seriously questioned for it would surely lead to an accelerated erosion of the major picturesque, cultural and even economic characteristics of the original milieu represented by the Hundred Islands.