This one is from a future where a new cold war has started and nowhere is safe. not even the bottom of the ocean.
Patrolling along the depths of the sea are these behemoths. Giant genetically engineered crabs, retrofitted with all kinds of hardware. Piloted from a cockpit build into the crab’s own armour. Specialized weaponry and heavy natural armour, make it a hard target to take down. The Crab is effectively brain-dead, leaving only the pilot in control. The weapons system and motor control is patched directly into the crabs nervous system. This innovation increases reaction time greatly. In this future world animal rights activists have succeeded in freeing some of these monsters and releasing them into the wild. A population of wild Giant crab has perpetuated making the north Atlantic a dangerous place to tread. Thankfully the sheer size of the crabs make it impossible to exit the water.