Sea and Sea Motomarine II help required

I need some advice on focus settings for Motomarine II when using the 16mm W/A converter. Do I just set the focus according to the standard focus adjustment scale? I'm on a dive trip in Western Australia at the moment and my camera has flooded, but I've been loaned a Motomarine for a few days. Any help very much appreciated.

Just preset to infinity.

But don't expect very good images: exposure is a nightmare, particularly after the joys of digital underwater photography.