ILM's first breakthrough: a motion control camera, which could revolve repeatedly around stationary objects while remaining in constant focus, thus simulating flight.

FORBES: Entertainment

Rollhaus eventually scrapped the cumbersome water bumper -- which only worked for collisions up to 20mph -- in favor of cushioning stationary objects like lane dividers.

FORBES: Crash course

Coast Guard records show the Seastreak Wall Street was involved in seven incident investigations between 2006 and 2010, including four in which it was damaged in collisions with stationary objects such as docks or pilings.

WSJ: Dozens Injured in Manhattan Ferry Crash

One constant so far, though, is that all of the objects being hidden are stationary and very, very small.

FORBES: Duke Researchers Perfect The Original Invisibility Cloak