I would go for a new GMT. You can use it to time things (position the bezel marker and read off the dial's minute track...if it works for Unimatic, it can work for Rolex) and tell time in different locations. The crown is properly proportioned and no longer looks dinky like many of the earlier models. It has a ceramic bezel so no fading, the colours stay bright. The current GMTs are great watches. I wouldn't worry about a sub...you are much better off with a Sea Dweller!