Mariana County

Mariana County is due to appear in Grand Theft Auto VI as a county in the southern region of Leonida. Publicly available material places the Grassrivers and Leonida Keys regions within the county, though only limited information about its boundaries, roads and settlements has been disclosed. Its name is identified ahead of the game's release, rather than through a detailed official description of the area.

Mariana County is first named on an Interstate 404 sign in Port Gellhorn during the second trailer. The sign lists Mariana County alongside Vice-Dale County, connecting it to Leonida's highway network. This brief reference is the earliest stated appearance of the county's name in the material available so far. The trailer does not provide further details about the sign's destination or the county's extent.

The towns listed for Mariana County are Key Lento and Watson Bay. They sit alongside the Grassrivers and Leonida Keys as the named places associated with the county in the available material. No public description has yet established the size of either town, their local landmarks or how they connect to the county's other named regions.