
After a three-year overhaul and major upgrade, the United States' deepest-diving research submersible, Alvin, has been cleared to return to work exploring the ocean's depths.
After a three-year overhaul and major upgrade, the United States' deepest-diving research submersible, Alvin, has been cleared to return to work exploring the ocean's depths.
Marine cyanobacteria are the tiny ocean plants that form the base of the ocean's food chain. Other organisms feed on them and are nourished by the oxygen they provide.