A dive in Cenote Angelita, near Tulum, Quintana Roo, Mexico with Danny Riordan.
Angelita is a water-filled natural inland sinkhole nearly 60m deep; the top part down to about 30m depth is fresh, below that is salt water. The fresh water is clear below a layer of algae in the top few metres, which filters the light to a dim green. Trapped just above the boundary between the salt and fresh water - known as a halocline - at 28-30m depth is a thick milky layer of dissolved hydrogen sulphide emitted by rotting vegetation, below this the salt water is again clear but very dark.
Maximum depth of this dive was 48m, total time 65 minutes.
Filmed using a Sony NEX-5n with 10-18mm lens in a Nauticam housing and twin Mangrove video lights.