Do Scuba Divers Need to Carry a Scuba Dive Knife When Underwater?

Carrying a scuba dive knife looks impressive, but is a knife a necessary item of scuba equipment on all scuba dives? A knife can provide a sense of physical security, but in most scuba dives it is probably an irrelevant item of scuba equipment.
For example, it would be difficult to justify carrying a scuba dive knife on a simple dive at one of the many coral reef dives on Australia’s Great Barrier Reef.
Fishing Line and Carrying a Scuba Dive Knife
A scuba dive knife could be handy when diving on a site covered with old fishing line and the scuba dive plan is to recover some of the lost sinkers for making into scuba dive weights. Prising the sinkers and fishing line out of the nooks and crannies of the underwater seascape with a scuba dive knife may be a good justification for carrying the knife.
From a safety point of view, a knife would be very useful, maybe even a life saver, to have when fiddling around with fishing line underwater. A scuba diver can quickly get tangled and caught up in the old fishing line which can lead to all sorts of problems. A quick flick with the scuba dive knife can cut away any problems.
Wreck Diving and Carrying a Scuba Dive Knife
A scuba dive knife might also be a useful item to carry when diving on a wreck. It might be needed to prise away a wayward piece of wreckage or debris that might move while the diver is penetrating the wreck.
There could also be the problem wayward fishing line, as mentioned above. Or there may be old ropes and other bits and pieces to be cut away.
Carry a Scuba Knife When Exploring New Scuba Dive Sites
When exploring new scuba diving sites, a knife would be a useful item of scuba equipment. At a new site, without benefit of personal knowledge (or local knowledge from the local dive club or shop) a diver might come across some unknown problems that may be best resolved with a scuba dive knife.
Reasons to Carry a Scuba Dive Knife
Some other reasons for a scuba diver to carry a knife could be:
•Diving in heavy seaweed, such as kelp
•Search and recovery type dives where ropes and the possibility of getting tangled may be present
•Drift dives where there could be the possibility of getting tangled in the rope dragging the scuba dive flag
•Equipment failure may lead to problems underwater where a knife may need to be used to cut-away equipment. Maybe the weightbelt buckle can’t be opened due to damage; or a similar problem.
•It could be useful for divemasters or scuba instructors to carry a knife in case students may need some assistance with equipment.
A Scuba Dive Knife and the Marine Environment
One of the reasons for many scuba divers to carry a knife is to pillage the ocean. Carving off oysters, coaxing crayfish out of a crevice or opening anemones to feed the fish are all uses for a knife.
Using a knife for this type of activity should be discouraged. Interaction in this manner by scuba divers with the marine environment is not good. It not only kills off the life, but also decimates the environment for future divers.
The image of a rugged scuba diver battling a ferocious, teeth filled shark is something that should be left to the realms of fiction. Not only would it be near impossible for a scuba diver to kill a shark with a scuba dive knife, it would be extremely dangerous with a wounded shark flapping around.
Communicating With a Scuba Dive Knife
It may sound a bit strange to communicate underwater with a scuba dive knife, but it is possible. The knife can be used to gain a dive buddy’s attention. Banging a knife on a steel or aluminium tank is one of the best ways to get the attention of another diver.
A simple message previously developed with the scuba dive buddy could be used. It would even be possible to tap out Morse code on the tank!
There are specific reasons for a scuba diver to carry a knife. However, a knife should really only be carried if warranted by the expected diving conditions.