Underwater large format polaroid photography

I would never have thought that this is technically feasible in a usable manner. - 4x5 large format polaroid camera in a underwater housing.
But, apparently it worked out. Ian Erik Regnard was running a respective project. Visit his on-line gallery for results: link
There are some interesting shots of reef sharks.

Michael Zhang compiled a blog post on petapixel.com entitled "Underwater Photos with a 4x5 Large Format Camera" showcasing this special project: http://petapixel.com/2016/02/27/underwater-photos-4x5-large-format-camera/