] "In 1999, construction began on a new breed of attack
] submarines that won't have a periscope. Instead, these
] new Virginia-class submarines will use non-penetrating
] imaging devices called photonics masts to perform
] surveillance tasks. Each new submarine will be equipped
] with two photonics masts, which are basically arrays of
] high-resolution cameras that capture and send visual
] images to flat-panel displays in the control room."

Nifty. Now you know. This section also has lots of links to a lot of other interesting pages about the Virginia class submarines. My job is neat.