Workshop link: https://steamcommunity.com/sharedfiles/filedetails/?id=3136595632
Mule is a modification of a standard heavy lifter submarine model commonly utilized in mining, construction, and wreck salvaging operations. Modified with the same parts it used to salvage, the Mule was turned into a slightly more versatile Transport class vessel, compared to the original model.
Filling the Transport class shaped hole in the selection of submarines you can start the campaign with, with medium starting funds, the Mule allows you and your crew to live that underwater trucker life from the get-go.
You'll get the most out of the early-game cargo missions and will have a slightly easier time looting caves and wrecks (if any), thanks to the crate shelf installed outside, on the diving platform.
If you use it in your campaign, let me know how it goes.