Dive Newcastle has a great range of scubadiving Knives.
A dive knife is a general tool and safety device. In the latter case, you use it in the unlikely, but possible, situation that you’re entangled and need to free yourself. A dive knife is a key safety tool to help you if you get caught in fishing line, nets, seaweed, etc. It is not to fend off attacks from underwater creatures. It is not a weapon.