The French company DCNS developed an interesting concept ship which is essentially a stealth submarine which operate very close to the surface of the water.
The SMX-25 will be cheaper and easier to build and operate than a conventional submarine but will still have many of the benefits including very low signature, making it hard to detect.
DCNS envision the SMX-25 to be powered by three gas turbines driving three water jets and submersible is designed to achieve a sustained surface speed of 38 knots.
