buoyancy - the ability or tendency to float in water
carapace - the hard upper shell of a turtle
cold stunned - the hypothermic reaction that occurs when sea turtles are exposed to prolonged cold water temperatures. Initial symptoms include a decreased heart rate, decreased circulation, and lethargy, followed by shock, pneumonia and possibly death. (NOAA)
neutrally buoyant - a condition in which a physical body's average density is equal to the density of the fluid in which it is immersed. For turtles this means that they are able to maintain a depth in the water column with out fighting to not sink or float.
plastron - the part of a turtle's shell forming the underside.