The Ocean Observatories (OOI) Initiative uses a wide variety of ways to capture ocean data. In some cases, sensors are attached to buoys at the ocean's surface that are anchored to the seafloor. Some anchors are in water as shallow as 24 meters (80 feet) deep in some areas, but in others, they are sunk as deep as 6,100 meters (20,000 feet). The sensors attached to these buoys measure properties such as ocean currents, temperature, pH, and carbon dioxide levels at the boundary between the ocean and the atmosphere. They also measure the state of the ocean from top to bottom. The data from these buoy sensors return to shore for analysis via satellites.
We also gather data using cables that extend along the seafloor from ashore. These cables feed lots of electrical power to sensors at the surface, on the seafloor, and into sensors floating on tethers well above the seafloor. The cables provide communication speeds that are tens of thousands times faster than the network that comes to your homes for computers and televisions. The sensors can record data almost without limit in capability. Imagine, for example, 3-D movies (like Avatar) coming from the seafloor of animals never before studied!
Finally, new moveable instruments are being placed on unmanned vehicles that can wander the ocean, occasionally communicating by satellite, to deliver data and to receive a new set of orders. These new vehicles travel from the ocean’s surface to great depths collecting data while also extending the scientific reach of the OOI measurements being collected only at the fixed buoys or seafloor cable locations.
--John Orcutt, professor of geophysics, Institute of Geophysics and Planetary Physics