Welcome back to another Seiko-flavored edition of Historical Horology. Last week’s dive into the Seiko Monster proved popular, which makes sense. The Monster is a popular entry-level diver, and it is also one that John and I have recommended quite a bit. While that last article really was more of a look at how the watch and it’s movement are put together, this week we do have a more historical look at the Seiko Tuna. It’s not a particular deep history, considering that the watch was introduced in 1975, but it is a history nonetheless.