Ocean Networks Canada (ONC) operates and maintains innovative cabled observatories that supply continuous power and Internet connectivity to various scientific instruments located in coastal, deep-ocean, and Arctic environments. The Clayoquot Slope IODP (Integrated Ocean Discovery Program) borehole observatory CORK U1364A is located in the Vancouver Margin of the northern Cascadia Subduction Zone, ~20km landward of the accretionary prism toe. Here, sediments scraped from the subducting Juan de Fuca plate are deposited and the accreted sedimentary section is ~5 km thick with gas hydrate formation in the upper hundred meters of sediment. The CORK (Circulation Obviation Retrofit Kit) observatory was installed in 2010 during IODP Expedition 328 (Davis & Malone, 2010; Davis & Heesemann, 2011). This location was chosen to observe the fluid flow, mechanical and formation properties of the accretionary prism, allowing for long-term monitoring of deformation, seismic activity, and gas hydrate accumulation. In May 2014 a temperature profile was measured by lowering a CTD (Conductivity-Temperature-Depth) down IODP borehole observatory CORK U1364A. The CTD profile was obtained during Ocean Networks Canada NEPTUNE Maintenance Cruise 2014-05 using the remotely operated vehicle (ROV) CSSF-ROPOS from the CCGS John P. Tully. Dive log entries are available from Dive R1694 and a video recording of the experiment is accessible through SeaTube, ONC’s video player (https://data.oceannetworks.ca/SeaTube?resourceTypeId=1000&resourceId=1001&diveId=410&time=2014-05-24T15:43:08.000Z). CTD data was collected using the factory calibration settings and downloaded from the instrument using the CTD manufacturers software. The initial purpose of this experiment was to determine the open depth of the borehole. The data of the hydrological observatory have been used in multiple subsequent studies to investigate pressure and temperature changes of the subseafloor (Becker et al. 2020, Mcguire et al. 2018). Boreholes drilled within the accretionary prism help to better understand the relationship between dynamic processes such as tectonic motion and deformation, internal plate strain, and earthquakes, as well as gas hydrate formation and accumulation.