Outside my window, the South Atlantic lay unbroken—an azure expanse of ocean below and sky above. Three hours after passing the Namibian coast, a lone patch of clouds appeared on the horizon. As we approached, I could just discern patches of green peering through. Atop a narrow ridge, a tiny strip of runway appeared, the sheer drops at each end plummeting to the sea.

Adobe Photoshop is the number one tool for image editing and provides a large number of editing tools and options—far too many of them actually. But the good news here is that, for editing our underwater images, we only need a few.

I started cave diving in Italy in 1990. At that time, the rules were very clear, codified and related to the kind of caves that were encountered in my region. Very often, they were resurgences with current (sometimes strong) or sumps inside caves, with water ranging from crystal clear to the color of coffee and variable visibility, depending on the rains.