A big cast net is a reward for completing the quest Deadliest Catch. It is wieldable in the off-hand slot, has the same function as a big fishing net, but saves one inventory space. Players can get multiples from Jones the fisherman without employing the drop trick. It, as well as the small cast net, can be stored inside tackle boxes from Fish Flingers.
Due to the release of the tool belt, small and big cast nets became largely useless, serving mainly as cosmetic equipment.