This record describes data from the : Cloud Condensation Nuclei Counter (CCN) collected on the Marine National Facility RV Investigator Event voyage IN2015_E01. This was a cold-water trial voyage for the RV Investigator departing Hobart on the 29th January and returning to Hobart on the 18th of February, 2015. The CCN was performed using instrument DMT CCN100. It measures the number of particles that are able to form CCN at 0.05% supersaturation. Calibrations carried out by voyage scientists.