When you go on a dive liveaboard for the first or hundreth time I found these items essential. And once your on the boat - way out at sea you can't purchase anything - so being prepared is essential
Ear drops. Natural or medicated. You're going to be giving your ears a good work out diving multiple times a day
Ear Drops
Personal Locator Beacon. Pray you never need it - but always have it with you
A Guide To Personal Locator Beacons (PLB) For Scuba ...
Conditioner! You know why
Our Best Conditioner for Dry Hair: 25 Formulas to Try in 2023
You are constantly going in and out of the water. This is a great item to just throw on between dives.