Intended for "an undisclosed foreign government" the contract for the Glock 19 Mariner was not completed and these interesting and very functional collectibles are now filtering out to the market.
The Mariner label dates to at least 2005 and was used by Glock in marketing to countries in the Pacific Rim (Indonesia, Malaysia, the Philippines, Taiwan, Thailand, and Singapore are all military/police Glock-users) and elsewhere for models that include "Maritime Spring Cups" as a standard item.
As explained in ads for OEM Glock Maritime Spring Cups:
This is an internal part that captures the striker spring in the slide. It allows water, oil, and debris to exit the firing pin channel. This enables the pistol to be fired after it’s been submerged in water and in extreme hostile environments without field stripping the slide assembly.
The cups themselves have been the subject of internet legend for years.
While you can add Maritime Spring Cups to any standard Glock handgun, the Mariners come with them already installed from the factory. Are you really going to need them? Probably not, but to borrow a line from McConaughey, "It'd be a lot cooler if you did."
The Glock 19 Mariners that recently hit the marketare rare birds in the respect that they are U.S.-made, with Georgia rollmarks and stamps on the frame, slide, and barrel in addition to the "Mariner" laser engraving on the slide. They also include three Glock 19 mags with OEM +2 base plates and inserts that are cut for an ambidextrous magazine release.
These Gen 3 Glocks, other than the “Mariner” laser engraving on the front ejection port side of the slide and the +2 mags, have few other external differences from other Gen 3 G19s.
Of further interest to collectors, while most Glock factory clamshell hard cases in circulation here have either red, white, or blue labels depending on the program they were made for, the Mariners have a fluorescent green label denoting they are of U.S. Manufacture intended expressly for export.
To be clear, the Mariner Gen 3 G19 isn't revolutionary in itself, but it is an unexpected sight on the U.S. market right now that, like a prized billfish, you'd hate to let get away.