On a Bonaire trip last fall, someone's unsecured rig fell over and hit another diver who was leaning over to zip his boots. It glanced off his head and left a nice gash that needed to be glued to close. He missed 2 days of diving due to someone's else's negligence (unintended, of course) - always secure your gear!as @scubadada says, always bungee your tank (or put on the deck on its side). In 2017 I was in Roatan, Honduras and someone on my boat didn't secure their bcd/tank/reg. It fell over and smashed the plastic elbow that connects to the BCD's corrugated hose. I don't believe he was able to find a replacement during that trip. That would be a real bummer, to have brought your stuff and still ended up renting.