The drysuit needs an air supply to prevent it getting squeezed at depth, and this uses another air-feed hose from the regulator. The inherent buoyancy of a suit makes a diver float, so lead weights are normally worn on a weightbelt to compensate. Sometimes these instruments are mounted on a console at the end of a hose. A submersible lamp is used to light the way at night, inside wrecks and caverns, and in other low-light conditions. A knife is used to sort out any possible entanglement in old fishing line, and a surface buoy attached to a line and winder-reel allows people at the surface to track the diver's position.
Underwater photography is an increasingly popular hobby - but that's another story.