Nikon Protector AA-15A

Underwater Lens Protector AA-15A Underwater lens protector designed for specific KeyMission cameras. The protection glass is flat, to enable sharp focusing in a marine environment. Use when submerged to protect the lens from dirt, marine particles, and disturbed sand or silt.¹
¹ There are shooting ranges that cannot be captured underwater because the images are magnified compared to images captured on land. Therefore you cannot capture 360-degree images. If shooting with the underwater lens protectors attached, the protectors create a black border or band around the image.