1 - fully charged camera battery
2 - camera battery charger
3 - spare camera battery?
4 - camera, soft case and lens cap
5 - spare camera?
6 - alternative lenses and adaptors
7 - filter material or filter lens
8 - underwater housing
9 - replacement housing O-rings
10 - O-ring gel
11 - housing weights (for neutral buoyancy)?
12 - housing loupe hood/ shade
13 - camera lens cloth
14 - laptop/ spare storage/ back-up for photos
15 - fish and/ or coral and/ or critter guide
16 - goggles/ mask
17 - snorkel
18- fins/ flippers
19 - weight belt
20 - lead weights
21 - reef shoes?
22 - suntan cream
23 - scalp protector/ swimming cap
24 - snorkelling bag