FM 5-490 Engineer Diving Operations provides the doctrinal basis for planning and using engineer divers in the theater of operations (TO). It describes responsibilities, relationships, procedures, capabilities, constraints, and planning considerations in the conduct of engineer underwater operations throughout the TO.
As a teenagers, I spent my summers diving for mussel shells in the Tennessee river, so I have some diving experience. Of course shell diving in the Tennessee river is nothing compared to military diving. We took CO2 tanks from soda machines and connected them to an air pump ran by a lawnmower engine. The makeshift air tank was run through a PVC pipe filled with broken charcoal if you were high class, most divers ran the tank directly to the air line. The air line was made of 100 feet or so of off the shelf air line duct taped to a nylon rope. This line was attached to a weight belt and terminated in a normal scuba regulator.
Shell divers tied a laundry bag to a loop of garden hose, slipped it over their head, filled the lawnmower engine and stepped of the boat to sink to the bottom of Kentucky lake.
To search for shells divers lay on the bottom of the lake in 6inches or so of mud and made mud angels to feel for shells. Visibility was measured in inches and it was not healthy or fun work. I think I would have much rather been a military diver, their work is not healthy or fun either, but at least their equipment worked….FM 5-490 Engineer Diving Operations