This is fun smile...

4 solar lights - cuts down on battery use
Solar battery
String back packs for going ashore
Underwater flashlight
2 walkie talkies - for ship to shore communications (no need to add phone charges for short range chatter)
Dry pouches for cell phones, credit cards, cash and a larger one for documents
Croakies
Ginger gum
12V USB chargers, plus 110V when you're running the inverter
Music source - mp3 player, phone, etc - I leave my vinyl at home smile
Auxiliary cable to connect music to stereo
Underwater camera
Sailing gloves