I am creating a population of human fish that has created a city in an oceanic trench.
There are few things to know about this kind of people and the place where they live:
- they are a bit stronger than human (the average fish-man is as fit as a professional athlete)
- they can freely breathe underwater and out of the sea as well
- depth as no effect on them
- the city is illuminated by a intensive farming of the same bacteria used by lamprey
- they have access to all technology of today (it's OK if their weapon can only be made on earth, they have good commercial relationships with classical humans)
I have already thought about melee weapons but I want to know if at this depth, with enough budget on research we could make at least a working harpoon thrower. Even if there is no way that they could manually pull the string themselves, they could at least use it one time.
I don't want a weapon of mass destruction, but things that a single person can use.
And if there is a way to get a weapon like that, would it be usable outside water or at a lower pressure too?