How to get Hydra in GTA 5?

Excuse me, I'm curious about something. Could you please explain to me, in detail, how one might acquire the currency known as Hydra in the popular video game Grand Theft Auto 5? I've been hearing about it, but I'm not entirely sure of the steps involved in the process. Perhaps there's a specific mission or set of tasks that need to be completed? Or maybe there's a specific location where it can be found? I'd really appreciate any information you have on the subject.