A freediving instructor waits for their student to return from a dive below Cenote Angelita’s microbial cloud – a cloud that separates the light-filled freshwater above and the dark saline water below. “The microbial cloud is so thick that it appears to be a floor,” says photographer Jason Gulley, “and visibility inside it is almost zero. Visibility improves a little as you re-emerge into the pitch black saline water below.”