We scuba divers tend to make fun of our buddies who jingle and jangle due to a bunch of accessories attached to multiple D-rings and jammed into BC pockets. But some accessories come in handy and make your dive easier. And in a serious emergency, some accessories could just mean the difference between life and death. You may not need to take all 20 of these on every dive, but make sure you're prepared for the day's dive conditions, and then accessorize appropriately.

1. GPS Locator

Nautilus Marine Rescue GPS If you dive in current, open ocean, alone or just want the ultimate in safety devices, you should absolutely have the Nautilus Marine Rescue GPS. Just under 3 by 4 inches, it weighs 5 ounces, and is positively buoyant and waterproof to 425 feet with the cap closed. The battery is replaceable and designed to last five years, and a simplified operation: At the surface, open the case, pull off the plastic cap to let the springlike 9-inch antenna unfurl, turn it on, and press the red button. The LifeLine will broadcast a digital “man overboard” signal with GPS coordinates of your location accurate to 1.5 meters to any vessel within 34 miles equipped with the marine Automatic Identification System (required for most cargo and all passenger vessels) as well as a digital message to the marine radio on your own vessel. $179; nautiluslifeline.com

2. Knife

Spyderco Dragonfly Hawkbill This is the newest version of well-regarded knife maker Spyderco’s immensely popular Dragonfly 2 Lightweight. This compact knife has it all — it combines the proven design of the Dragonfly 2 platform, the incredible rustproof qualities of H-1 steel, and the extreme cutting power of a hawkbill blade.In our knife tests, the Dragonfly was able to cut any material we threw at it. It's the perfect tool for cutting netting, line, and other fibrous materials. $97.95; spyderco.com

3. Dive Light

Scubapro Nova 2100 Spot Flood Whether you're a night or cavern diver or just like peering into the recesses of a reef, you need a dependable dive light. The powerful Nova 2100 SF multiuse dive light features two beams and five light modes plus an emergency signal to match virtually any diving situation. Dual beams include a 2,100-lumen 65˚ wide beam, and an 800-lumen 15˚ spot beam. It comes with multiple handles, accessories and spare parts in a carrying case. $600; scubapro.com

4. Backup Dive Light

SL653 Sea Dragon Mini 900 Lumen Dive Light Perfect as a backup light due to its ultracompact size, the 900-lumen Sea Dragon Mini offers users tremendous brightness and a 14-degree long-range beam. All light functions are easily accessible, with only one hand needed to cycle through five light modes, including three brightness levels and two emergency signals. Features up to 8 hours burn time using an 18650 battery. $79, sealife-cameras.com

5. Beacon Light

IST Sports Beacon Lights IST Sport’s multicolored beacon lights offer an inexpensive and simple way to keeping track of everyone underwater during a night dive. Small and powered by three microcell batteries, the Dive Beacon comes in four colors. It twists on and off, and can be attached to your BC or tank valve with the included lanyard, or you can zip-tie it anywhere it’s best seen by your buddy. $8; istsports.com

6. Safety Sausage

Divers Alert Network Signaling Sausage If you dive in current, from shore, or alone, this should be standard equipment for you. Our safety signaling gear test showed that the bright orange color was best for most conditions (sunny days, overcast conditions, etc.). This 6-foot orange sausage is now made with 2-inch reflective strips on both sides and a radar reflective panel located on the inside of the tube. It has a low-pressure inflator attachment, Velcro mesh storage pocket and secondary lift bag with 30-pound lift capacity. $60; diversalertnetwork.org

7. Whistle

Windstorm Safety Whistle We loved the piercing sound — 120 decibels — of the Windstorm Safety Whistle when we tested it several years ago. Developed for military use, the Windstorm can be heard up to 50 feet away underwater; even farther at the surface. Made of durable thermoplastic. $6.95; divers-supply.com

8. Signaling Mirror

Divers Alert Network Rescue Flash Signal Mirror It is one of the expensive items you can add to your surface signaling arsenal — DAN’s Rescue Flash Signal Mirror. This durable reflective mirror is visible for more than 20 miles. Instructions for use are on the back of the mirror. $5; diversalertnetwork.org

9. First-Aid Kit

Divers Alert Network’s Coast Guard Complete First-Aid Kit Make sure you’re prepared in an emergency. More than 200 premium first-aid components are included in a waterproof hard case. This kit meets the Coast Guard's requirements for small passenger vessels. $160; diversalertnetwork.org

10. Alternate Air Source

Submersible Systems Spare Air Why not carry the Spare Air, with just enough air to give you a couple of extra breaths in an out-of-air emergency? You can refill easily from your own tank and it includes refill adapter. It attaches to your BC with included holster and safety leash. spareair.com

11. Dry Bag

Cressi Dry Bag OK, this might not save your life, but it might just save everything you need to keep dry, like a change of clothes, your phone and wallet. It is the ideal bag for carrying your equipment in any challenging situation, including the dive boat. This bag has electronically (RF) welded seams that make it 100% waterproof. The design provides all-purpose and reliable protection for your gear. cressi.com

12. Regulator Bag

Cressi 360 Regulator Bag Your reg is one of the most important life-support items of gear that you own. Shouldn't you treat it the same way as a guitar, camera or binoculars, all of which are usually transported in specially made cases? This durable, well-made padded bag will safely transport your regulator or other delicate instruments. Fitted with shoulder strap. $29.95; cressi.com

13. Octo Reg

Cressi Compact Pro Octo In the unlikely event that your buddy has an out-of-air emergency, you'll be happy that you can hand off the XS Compact Pro Octo, which uses the same materials and casing as the Compact Pro reg, which is made from durable hi-tech polymers. When things are going south for a diver who may be panicking, the bright-yellow cover is a safety feature. This easy breather will deliver air and help calm your buddy while you ascend. $129.95; cressi.com

14. Compass

Cressi Luminous Compass Never get lost again and navigate in dark or murky water with Cressi’s easy-to-read compass. It has a highly luminous dial for easy reference in low-light conditions. $29.95; cressi.com

15. Tank Banger

Trident Tank Banger Signaling Device Nothing is more frustrating than trying to get your buddy’s attention when a hammerhead shark is behind her. Trident’s Tank Banger Scuba Diving Signaling Device is simple in its construction — basically, a rubber band and ball — and simple to use underwater — put it on your cylinder, and when you see a whale shark, hawksbill turtle or spotted eagle ray, just stretch the band away from tank, let go, and let the ball make a loud thwack. Available in multiple colors. $6.99; divers-supply.com

16. Boat Bag

Cressi Gorgona Boat Bag This mesh bag is a practical way to carry or rinse all your scuba equipment, and is perfect for using as a portable dive boat bag. Its length will swallow even the longest freediving fins. $29.95; cressi.com

17. Mask Defog

McNett Sea Drops Alright, it won't save your life, but it will keep you from getting aggravated at a constantly fogged mask — McNett Sea Drops. It’s what we use when we’re testing gear, especially masks. A quick application of Sea Drops cleans lenses and gets rid of fog, giving you a crystal-clear view of the reef, wreck, shark or whatever you’re hoping to see. It’s safe for silicone and rubber frames, long-lasting and non-abrasive. $4.99, divers-supply.com

18. Neoprene Patch Kit

Stormsure Neoprene Queen Adhesive and Patches Stormsure calls its neoprene adhesive and patch kit “first-aid for wetsuits." Maybe not a life-saving item, but it could be a dive-saving one, especially if you dive in chillier waters and split a seam on your wetsuit. Neoprene Queen is a black liquid neoprene adhesive that can glue rips, splits, unstitched seams, damage in your wetsuit. You can use it with or without a patch, and you can get back in the water in just a few minutes. The blister card contains a 30gm tube of quick-drying contact adhesive and 5 circular neoprene patches. $9.95; divers-supply.com

19. Soft Weights

Seasoft Scuba Seabags Most people need at least a little bit of lead to descend — why not choose soft weights that are ocean-friendly? The lead shot in Seabags is coated with a catalyst and tumbled in graphite flakes to create a hard double coating that seals in the lead and prevents it from oxidizing and potentially damaging corals — plus they’re easy on your waist and hips. The bags are made of rugged neoprene and sewn closed with five passes of heavy-duty nylon thread. Seabags are available in 2, 3, 4, 5 or 10 pounds and are color coded by weight for easy reference. $4.99 per pound; seasoftscuba.com

20. Mesh Bag

Innovative Scuba Concepts Econo Mesh Drawstring Bag This one is because we should all do our part. The Econo Mesh Drawstring Bag from Innovative Scuba Concepts comes in three sizes (16 x 20, 18 x 30 and 24 x 36 inches). This is not a heavy-duty goody or catch bag (for lobster, lionfish, etc.), but it’s the perfect size to tuck into a BC pocket in case you come across some plastic or debris during your dive. There’s a nice D-ring so you can attach to your BC, keeping your hands free to do the collecting of ocean trash. $5.95; divers-supply.com