Horological Meandering

I recently bought this Vintage Skin Diver which is in nice condition IMO. Of course the original box is a nice add-on (no papers however). It has a 37 mm case. I love the nice patina of the tritium lume. Upon close inspection, there is some loss of lume. ...  

Have u checked the crown ?is it screw down?

Nautiluses were all w/o .nice watch , enjoy it!