I carry light, smb(with spool) and whistle on every dive and will add a mirror and a extra smb on LoB. But how many divers I had came across over last 25 yrs did the same?
Why would I need to carry a light for day dive is the most common question.
The line on the spool is very very useful.
As for PLB: I was loaned one on a trip to Cocos by the boat operator(Undersea Hunter).
The Divesoft Fluorescein Dye marker leaves a substantial discoloration of a huge amount of water in your immediate area which greatly increases your visibility for both the dive boat as well as air support. It significantly increases your chance of being spotted in am emergency situation.
www.divegearexpress.com
Only once that one diver carried water and energy bar!