America has a mighty, might navy, with giant, powerful ships that are (or soon will be) outfitted with laser canons and hypersonic railguns, but these fearsome war machines have one major weakness: land. DARPA's new CAAT demonstrator can project some of this power onto the shore, using big air-filled flappy bits to allow vessels to travel on water or land.
The CAAT, or Captive Air Amphibious Transporter (a slightly strange acronym for a vehicle mostly at home in water), is part of a DARPA's Tactically Expandable Maritime Platform program, which leverages "innovative technologies to transform commercial container ships into self-contained floating supply bases during disaster relief operations, without needing port infrastructure." So yeah, you can forget about the bit regarding the lasers and railguns: so far, the CAAT is just for humanitarian work.
You can think of the CAAT as a tank, where the tank treads are made of soft floppy things filled with air. This not only allows the CAAT to float on water, but also crawl over all sorts of obstacles. With only two pounds per square inch of ground pressure, I bet that you could get run over by this thing while napping on the beach (like we bloggers do all the time) and it wouldn't even wake you up.
With this 1/5 scale operational prototype, DARPA has finished its part of the program by saying, "hey, cool, that seems to work." It's now up to the Office of Naval Research to figure out whether the Navy or the Marines are going to try the CAAT out for themselves to replace the hovercrafts that they currently rely on.