| Underwater Search & Recovery Techniques|
While these techniques have worked well for me, I am not advocating their use by others. I am not a trained professional nor a certified instructor.
Historic objects Mark location and notify relevant organization. Why ? Submerged Historic Resources are often protected by state or federal law. Removal of such items (even if an isolated find rather than in situ) can place the diver into a legal nightmare. "experts" would prefer to lose access to a find and let the future "re-find it" than to have unauthorized removal of the item.
Explosives, old cartridges, explosive shells, cannon balls etc are best left where they are found and your local EOD contacted. In the US this is often the Military or State Police who will have an EOD person or a contact. Why ? as propellant dries, it can become unstable and detonate when jarred or spontaneously.
Mark the location
Firearms - unless a targeted search, a firearm might be related to a crime. Mark the location and inform law enforcement, noting the type, size, any markings visible. If part of an organized search and recovery is mandated, marking the location via float will allow law enforcement to estimate where the weapon might have been disposed from.