Chile has an economy that strongly depends on natural resources, mainly mining and agriculture. Water is a strategic asset for the latter. Considering the water strategic economic value and that due to drought, aquifer and reservoir depletion, water supply reliability has become a permanent problem in the country's most productive regions. The mining sector alone has planned for at least 19 projects using seawater in their processes. Considering the geological and tectonic context of Chilean coastline, these projects face significant difficulties. That is why subsea tunnels for intakes and outfalls are part of the solution to this challenge. This paper describes Chilean water context and design and constructability approaches for three different cases.