The very first attempt at underwater photography was by William Thompson in Dorset, UK, who in 1856 used a wet collodion glass plate camera to create the photo.
In 1893 French zoologist Louis Boutan shot the image listed as the world’s first underwater photograph. It was a first both in terms of being the first underwater photograph, where both the camera and the photographer were underwater. It was taken with a magnesium powder flash. Also, it was the first published underwater photograph. Some sources claim that the portrait was captured at a depth of 164 feet.
The image is listed as the world’s first underwater photograph.

The first underwater photograph was taken on a wet collodion plate in 1856 by William Thompson.

Louis Boutan’s underwater image taken with magnesium flash in 1893.
Romanian biologist, zoologist, speleologist, Antarctic explorer and Diver Emil Racovitza at Observatoire Océanologique de Banyuls-sur-Mer, France

The incredible equipment Boutan used to take the first underwater portrait.
