Imagine sitting on a battlefield and trying to figure out what is happening with only your ears to guide you; your guidance is based on orders written weeks or months ago, and the last time you got an update of where your own forces where was a day old (at best). That, in essence, is submarine warfare. There is no constant information flow for situational awareness and communication (of any kind) endangers your existence; so submarine commanders are required to make decisions based on a series of assumptions about a myriad of variables and use their experience, judgement, advice from their team, and a deep understanding of their adversary. Building people who can do this – so different to most other warfare experiences – requires a special process: The Perisher. Peter talks to Phil Titterton about command and control of submarines, his experiences in the Royal Navy's submarine service, and about waterspace management (submarine control measures). Now you can open your eyes.