Abstract: A manned submarine includes first and second side-by-side chambers extending in a fore-to-aft direction. The first chamber is maintained at substantially atmospheric pressure and includes sleeping and eating compartments for ship-based personnel, and a galley. The second chamber is maintained at greater than atmospheric pressure and includes sleeping and eating compartments for diver personnel. Passages interconnect the chambers, enabling ship-based personnel from the first chamber to service diver personnel in the second chamber. The submarine carries guides which can be mated with corresponding guides on a piece of underwater equipment to stabilize the submarine against lateral movement and allow the equipment to be attached to the submarine for transport. The submarine carries weights which are placed on the water bed and connected to the submarine by initially slackened lines.