A new deep-sea submersible.

Scientists from the Woods Hole (Mass.) Oceanographic Institution and the National Science Foundation in Arlington, Va., have announced a 4-year, $21.6-million design-and-construction effort to replace the aging research submersible Alvin.

Alvin, owned by the U.S. Navy and operated by WHOI, was launched in 1964 and has made more than 4,000 dives, enabling researchers to spend more than 16,000 hours observing seafloor environments throughout the world.

Design specifications for the replacement vessel include the capacity to dive to 6,500 meters, or 2,000 m deeper than Alvin. With that capability, the yet-to-be-named submersible should be able to explore more than 99 percent of the world's ocean floor, says Barrie B. Walden, project director at WHOI.

The new craft will have battery power more than triple that of Alvin and a maximum ascent and descent rate almost 50 percent faster, characteristics that will enable the new submersible to spend more time on the ocean floor.

The best enhancement might be the configuration of the submersible's view ports, Walden notes. The fields of view on Alvin's three windows barely overlap, so no two occupants can see objects simultaneously. On the new craft, a five-window configuration will permit the two scientists on board to more easily see what the pilot is looking at.