Practice the decisions you make underwater.

One control: hold to inflate, let go to vent. Boyle does the rest. Fly a new reef every day and race your own ghost.

Plan your turn pressure and minimum gas, then swim the dive. The reef pays more the farther you go. Your gauge says when to leave.

Your phone is the compass. Turn your body to set a heading, count kick cycles, and find your way back to where you started.

Three minutes at five metres on your breathing alone, while the swell, a light cylinder, the jellyfish and a jammed reel try to move you. A new stop every day.

Your buddy signals, you read it or answer it, against the clock. In murk you get one look. At night it is all torch. And OK is a question: answer with what is true.