This month, a slow-swimming robot known as Spray will attempt to glide roughly 2,484 nautical miles across the Atlantic, from the southern tip of Greenland to the coast of Spain. An autonomous underwater vehicle, or AUV, Spray is a joint venture between the Woods Hole Oceanographic Institution in Massachusetts and the Scripps Institution of Oceanography in California. When deployed, it will act as an aquatic sentinel, gathering data on temperature, currents and salinity that will help scientists better understand the role of oceans in regulating the global climate.

Since the bombing of the U.S.S. Cole in 2000, protecting docked ships-both military and commercial-has been a big priority in the fight against terrorism. The Department of Homeland Security has already awarded $489 million to help guard the nation´s ports, spurring a number of innovative ideas, the latest of which is an underwater system that blasts enemy swimmers with painful acoustic waves. Patented by the Raytheon Corporation last October, the system is the brainchild of former Navy and Raytheon acoustics expert Frederick Di Napoli. His scheme is simple: Generate a region of high-pressure, low-frequency sound around the ship, creating a sort of sonic fence that â€shocks†anything that swims through it. Although a diver would probably flee from pain, Di Napoli says, "you could really dial up the pressure and make it lethal if you had to."