Here are 21 of our favorite scuba diving gear accessories.

The sheepfoot-style serrated blade — our Editor's Pick for Best Accessory in our annual Gear Guide — is made of flat-ground VG-10 stainless steel, and has a blunt tip to reduce the chances of accidental puncture. The handle is textured with injection-molded FRN scales, so it’s easy to hold onto.

Contact: spyderco.com
MSRP: $180

This pack has a dedicated sleeve for a laptop, a fleece-lined compartment for a phone or MP3 player, padded shoulder straps with moisture-wicking mesh and two frontal pockets, each large enough to hold a mask box.
Contact: akona.com
MSRP: $88

Stahlsac offers a number of duffels; the HD is a durable bag made from a rugged tarpaulin fabric with a black-and-yellow color scheme. The duffel is perfect for transporting gear onto the boat or beach and can also double as your carry-on.
Contact: stahlsac.com
MSRP: $90

Carbon monoxide is deadly and gives divers little to no warning. This hand-held detector is simple to use for checking scuba tanks and works just like Analox’s popular O2 analyzer. No hoses or special equipment needed.
CONTACT: www.analox.net

This signaling device, which connects to a diver’s low-pressure inflator hose, combines an air horn for topside use and a percussive noisemaker for use underwater. Different models accommodate standard inflators and most inflator/ alternate-air-source systems.
CONTACT: www.divealert.com

Surface-signaling devices are considered a must-have safety item for many divers, and the Nautilus Lifeline takes that concept to a new, ingenious level. A combination GPS receiver and VHF marine radio, it gives divers the ability to speak with boats up to eight miles away. Plus, the system will broadcast GPS coordinates of the diver’s location to nearby vessels. A tough polycarbonate housing is rated to 425 feet and easily attaches to a BC’s D-ring. Battery life is 24 hours in emergency mode and, yes, there’s also a strobe.
CONTACT: www.divealert.com

Keep your iPhone, iPod or other mobile device safe while on the boat or beach. An external jack allows for headphones, and a rubber liner adds shock protection while doubling as an O-ring seal. Dimensions: 5.14 by 2.64 by 1.37 inches.
CONTACT: www.pelican.com

Great for using in the ocean or as the ultimate pool toy, the Aquanaut is built for kids up to 100 pounds. Small, light and positively buoyant, it’s easy to handle.
CONTACT: www.seadooseascooter.com

Designed to reduce jaw fatigue, the moldable bite tabs become ultra-comfy once conformed to the diver’s unique dental profile. A new, larger port increases airflow, and a special attachment seals the mouthpiece when not in use to protect regulators from debris. CONTACT: www.seacure1.com

These high-stretch UV-resistant silicone straps come with quick-release clips for added convenience. Available in three sizes, they are cool straps for Tilos fins and most other fins with post-style mounts. Comes in a two-piece package set.
Contact: tilos.com
MSRP: $46

Collapsible and weighing in at less than 24 pounds, this rig will haul up to 300 pounds of dive gear (or anything else) and makes it easy to move gear over rough terrain, up and down stairs, and even through sand. CONTACT: www.smartgearusa.com

You get 3 cubic feet of air (or nitrox) in a completely redundant, self-contained system that weighs just over 2 pounds full. Includes adapter for easy refills from a scuba tank, a holster to mount to your BC, and a leash. Click here for more info: http://www.sportdiver.com/gear/accessories/60second-scubalab-submersible-systems-spare-air-300

Not your typical slate- and-golf-pencil combo, the Kit includes the Aqua Pencil, slate, tether, lead and eraser. The unique pencil design is easy to deploy, use and stow — even with gloves — and is highly durable. CONTACT: www.xit404.com

This sleek-looking, 220-lumen flashlight from Ikelite is an impressive little torch. It’s great for helping you see what’s hiding inside dark holes and crannies in the reef.
Contact: ikelite.com
MSRP: Contact an authorized dealer

Great for carrying your favorite reg and dive computer, the Stahlsac Molokini can also be used as a laptop case or a carry-on bag. Features include both external and internal compartments, plus a sleeve for a 16-inch laptop.
Contact: stahlsac.com
MSRP: $65

A good choice for scuba and snorkeling, the Hydroflex provides enough warmth to keep divers comfortable while allowing freedom of movement. O-rings seal arms and legs, while a hook-and-loop collar adjusts to all neck sizes.
Contact: aqualung.com
MSRP: $115

This short-sleeved, loose-fitting top is perfect for wearing under a wetsuit or on its own to protect from the hot rays of the sun and the chilling spray of water. Made of water-repellent, quick-drying fabric with a SPF factor of 50.
Contact: scubapro.com
MSRP: $52

Benefit from both wind-chill and 50-plus UV protection with BARE’s long-sleeve rash guard made from a quick-drying, 6.5-ounce high-stretch fabric. Flat-seam construction eliminates chafing on bare skin. Available in three colors and four sizes.
Contact: baresports.com
MSRP: N/A

This battery-powered, temperature-controlled heated rash guard is for use under a wetsuit. It heats up in minutes and provides up to two hours of warmth to a depth of 150 feet.
Contact: thermalution.us
MSRP: $499

The high-cut Minorca 3 mm booties are ultra stretchy and come with rubber overlays on the heels and toes to resist abrasion from fin straps and foot pockets. They come in eight sizes for that perfect fit. Also available in 7 mm thickness.
Contact: cressi.com
MSRP: N/A

Easy to don and offering lots of finger dexterity while maintaining warmth, these 4 mm mitts are made with a stretchy neoprene with sealed seams to minimize water seepage. Carbonite texturing on the palms enhances grip.
Contact: fourthelement.com
MSRP: $52.50

For more brand-new accessories, check out the Gear Section of our website.