The CTD water monitoring sensor packages
A CTD is an instrument used in oceanography that contains multiple sensors attached to a single unit. The CTD is attached to a cable that is raised and lowered in the water column. Visit this site for additional information on CTD's.
Crater Lake owns two CTD units, one unit is deployed from the research boat Neuston and the other unit is permanently moored in the lake and takes a top to bottom measurement once per day.
Crater Lake biologists prepare the CTD for deployment by turning the power on and cleaning the sensor heads.
Getting the CTD ready for deployment.
The CTD sensor package is visible about 15 feet below the boat.
The unit is approximately 5 meters (15 feet) under the boat in the picture.