Seiko has a rather long and storied history designing and manufacturing dive watches, used by individuals from across the spectrum of jobs – from many of us desk divers all the way to Navy SEALs.
 
And there exist numerous vintage Seiko divers popular with collectors, and one of these is the sturdy diver here, a 1992 Seiko 7C46-7011 Marinemaster Professional (Ref. SBBN007) dive watch, affectionately referred to as the "tuna" by both Seiko and its collector aficionados due to its semblance to a circular tuna can.  Did we mention its fantastic matte-grey bead-blasted case?
 
Seiko first introduced their so-called 6159 “Grandfather Tuna” (you guessed it, the first Tuna – nicknamed after their distinctive shape) in 1975, and quickly followed with a number of similarly-designed divers through the 7549, and then introduced the 7C46 in 1986.  Within the 7C46 line, Seiko was intent on implementing more advanced materials on their top-grade watches – like the one here.
 
Per Fratello, "Seiko divers rank among my favorite watches of all time.  I tend to believe that Seiko has carved out a relatively unique design language for a genre that spawns multitudes of copycats.  Four-o’clock crowns, signature hands, and a penchant for simplicity are some of the traits that come to mind.  The Seiko [7C46] series that debuted in the mid-’80s is unmistakably a Seiko.  However, it’s different than anything else in the collection, and frankly, I love it!"  For an in-depth look at Seiko's Tuna divers, Fratello again has the answer, here.
 
An exceedingly rare variant of this watch here, Seiko produced a limited edition diver for ScubaPro, but this wasn't the first time the two teamed up to make a rare iconic dive watch.  In 1977,  the Japanese watch manufacturer took its 6306-7001 diver and made the 6306 Scubapro 450, produced in batches until at least till 1979.  And then did the same with the 7C46 in 1999, producing the Seiko 7C46 ScubaPro - both are true grail watches.  
 
This 1992 Seiko 7C46 diver comes on a new generic stainless-steel jubilee diver bracelet, and with nylon strap, rugged travel case, and springbar tool.