Distance to subject is the same for both of these photos taken with a Canon G2 camera in an Ikelite housing.

Camera lens is set to wide angle for the top photo. An optional Inon UWL-100 lens was added to the housing for the bottom photo.

The optional Inon UWL-100 wide angle lens or Sea & Sea wide conversion lens #58070 attach directly to the port.

The above lenses are not an Ikelite product, but are available from specialty underwater photographic dealers.