Water has several absorption peaks in the infrared. The first of these is at 976nm, the second at 1205nm, and the third at 1453nm. The objective here will be to photograph things at the first of the three peaks. (Part of the third peak has been shown in my prior work in SWIR, although I have not yet tried photographing using a bandpass exactly at that peak, as we will do in this case.)   The filter is the Thorlabs 980nm bandpass with FWHM = 10nm, abbreviated (by me) as "980BP10" in the graph bel