Sonar School of Fish

Advantages:

1. More data can be collected from the open ocean.
2. The fish can be used to track pollution spills or marine life.
3. These artificial fish are highly maneuverable.
4. The fish can move independently of one another or in small shoals to cover more area.
5. Using nature's propulsion methods could allow vehicles to be more efficient and maneuverable.

Disadvantages:

1. The radio signals used by the robotic fish travel badly in water
2. There is a possibility that the fish could get lost/separated if the signal gets lost.
3. Maintenance would be harder in the open ocean.
4. Other countries might not like the fact that the robotic fish are sending surveillance information about the water around their areas, even if it is in the open ocean.
5. There is always a chance that they could get eaten by a predator.

http://www.youtube.com/watch?v=Kk40ZnuzNNw