Beginning with OS X 10.9, Apple shifted gears naming OS X after big cats, and started using scenic spots in California (Mavericks, Yosemite, El Capitan…).

Curiously, El Capitan is a summit within Yosemite National Park. This is a subtitle hint from Apple, indicating that OS X 10.11 is more of a performance and usability upgrade, rather than a full featured upgrade.