What is the most expensive ship?

Question

is it titanic or what?

Answer 1

Currently the most expensive ship to build is the latest of the Nimitz  class of US Nuclear Aircraft Carrier. Somewhere around 7 billion dollars or more.

Answer 2

I'd say that the most expensive ships are either the USN boomers sub or the air craft carriers, and the most expensive non-navy ship is probably the Queen Mary 2.  The ship I'm on is a drill ship and cost 500 mill, and the new ones of the same class are costing 700 mill, but they don't hold a candle to those previously mentioned.