1st Dive Trip - Accessories?

[Ready4Launch]

I'm diving in Cozumel July 18-20 with Dive With Martin. Also diving July 16 in Mahahual.

Nice - enjoy. You're getting there when I'm going across to PDC.

 

[John Mooradian]

Snacks. Diving takes energy and long shallow dives can chill you sometimes more so than deeper shorter dives. A couple protein bars to snack on between dives and after diving while waiting out the boat ride back can be a huge help.

 

[EFX]

If you're diving with a computer bring spare batteries. I usually bring a small slate and keep it in my pocket. It can come in handy for those times when hand signals aren't getting the message across. You mentioned the mirror and others mentioned bringing an SMB, another important signalling device. All the advice on shooting an SMB (from a line) to hold a safety stop is puzzling. It's main use is to provide a depth reference in blue water and to alert the boat of your position. You'll probably be diving on reefs where the bottom, the boat, or the mooring line can be seen. If you can't hold a safety stop without hanging on to a line then practice your buoyancy until you can.

 

[Bratface]

If you have open heel fins, a second pair of dive booties is. When I dive multiple days, it's nice to have a dry pair.
A spare mask and save a dive kit as others have suggested.