Yes, the Canon EOS R fits in without any problems (as long as there is no telephoto lens on it). It is also waterproof. The only problem I had was that at a depth of about 13 metres, the camera is virtually vacuum-packed because the water pressure is so high. As a result, my shutter button remained pressed in and I couldn't take any more photos. This problem is solved by diving a little upwards.

Otherwise, it serves its purpose, but is rather cumbersome to use.