This dataset provides the conductivity, temperature and depth (CTD) measurements from the fixed-depth CTD sensors mounted on a full-depth mooring deployed by the SWOT prelaunch field campaign. The campaign was designed to test the performance of several instruments/platforms in meeting the SWOT Calibration/Validation (CalVal) requirement. It was conducted near the SWOT CalVal crossover location, about 300 kilometers west of Monterey, California between September, 2019 and January, 2020. These fixed-depth CTDs are below 500 m while the upper part of the mooring has a WireWalker (WW) profiler. The CTD data from WW is available here https://doi.org/10.5067/SWTPR-WW001. The campaign also deployed another two CTD moorings, a slocum glider, one bottom pressure recorder and one Pressure Inverted Echo Sounder. Details can be found in the user guide and the journal reference given in the documentation section.