I've lost a slate and flooded 2 divelights so far. This probably doesn't count: had a $500 Tokina wide-angle lens drenched in seawater on a small boat (caused by a rogue wave), but it wasn't on a dive trip.
Found a weight (encrustered with barnacles so I left it where I found it), a dive boat flag (over 2 ft diagonal).
I try to secure stuff I could lose during my dive by clipping them to my D-rings or tying them with zip-ties to attach to my BCD. But sometimes it makes them harder to access, which defeats the purpose of having them during the dive.
Found a weight (encrustered with barnacles so I left it where I found it), a dive boat flag (over 2 ft diagonal).
I try to secure stuff I could lose during my dive by clipping them to my D-rings or tying them with zip-ties to attach to my BCD. But sometimes it makes them harder to access, which defeats the purpose of having them during the dive.