Summary:
A list of items you should include when going diving that may not be obvious or seem necessary but would help to make your dive more comfortable and safe.
Don't leave the dock without it
When you pack your gear bag, your checklist probably includes the usual gear and emergency equipment, mask, fins, regulator and one of those kits with a few extra o-rings, neoprene patches and regulator mouthpieces. Here are a few extra things that you can throw into your gear bag that will make your dive more comfortable, confident, and safe.
Citrus beverages
When I surface, the first thing I want to do is get the taste of ocean out of my mouth. As much as I appreciate the smell of the sea and the salty air, I'm not so enthusiastic about having it on my tongue. Water is refreshing, but I find that I can drink a few liters of bottled water and still taste the remnants of the sea in my mouth.
After experimenting with dozens of beverage candidates, I find that Five Alive is hands-down the best cure for oceanmouth. Other citrus juices are good, but none are quite as effective as Five Alive. The better ones were those that contain acidic juices like pineapple and grapefruit.
The juice serves another purpose: rehydration. It seems counterintuitive that spending an hour submerged in water can cause dehydration, but it's true. The air in your tanks is very dry - necessarily so, since moisture in a tank will rust it from the inside. Just breathing in that dry air for an hour will silently dehydrate you. Drink something when you get back to the boat and you can avoid the symptoms of dehydration such as headache, nausea and dizziness.
Long-sleeved rashgard or cotton shirt
Did you know that the chemicals in sunscreen are poisonous to reef-dwelling marine life? You need to protect your skin from the harmful effects of UV radiation, but you don't want to slather on the SPF lotion before your dive. Cover up the old fashioned way with a cotton shirt or a long-sleeved rashguard.
Laminated Dive Table Chart
Are you dependent on your computer? Go back and review your certification training and learn how to calculate your residual nitrogen using tables. Computers are great tools, but it behooves every diver to remember how to manage their nitrogen levels without gadgetry.
A "dry bag"
A dry bag needn't be anything fancy - inexpensive bags with resealable flaps are available at most camping or marine supply stores. They don't need to be watertight to 100 ft - since you leave them on the boat in your gear bag. My favorite is a bright yellow, rubber bag with a top that folds over three times and tucks into itself for an easy watertight seal. Many divers on a budget will use a variety of disposable resealable freezer bags.
In my dry bag, I keep: