If you see a manual-winding Hamilton watch with a 10K RGP case you stand a good chance of guessing it's a "Sea Something". There are a bunch of models, starting in 1957, with "sea" in its name and the trend continued well into the 1970s with 10 or more models per year named sea-something.
One of the models you don't see very often is the 1962 Sea Scape II. It was offered for only two years. The dial looks very similar to a few other models but the sweep second hand is a unique feature. For example, this watch looks a lot like a 1960 First Mate.
The Sea Scape II is a nice watch but it's a bit of a sleeper ... it looks like any other garden variety model. However, it actually is a pretty unique model with a rare Hamilton caliber tucked inside. This is the only Hamilton model I've come across with a 678.