Ocean currents and thermohaline properties over the continental slope off northern Baja California are analyzed with data collected between 2008 and 2012. The data set is composed of 3‐year‐long time series of two moorings with current meter profilers and one chain of conductivity‐temperature‐depths, as well as data collected during 13 synoptic hydrographic surveys. The upper layer (<100 m) was characterized by low salinity Subarctic Waters. Geostrophic velocities suggest that waters of the lighter layer are advected equatorward by near‐surface flows. Below 50 m, poleward flow dominates, so the denser Subarctic Waters recirculates back north along the slope. The combination of geostrophic velocities derived from the hydrographic surveys and the current meter data confirm the presence of the California Undercurrent (CUC), a narrow subsurface poleward flow with a high‐velocity core confined to the continental slope. Mean core speeds were 12–15 cm/s at an average depth of ~150 m. Below the CUC, the core of spicy North Pacific Equatorial Water (NPEW) was found at a mean depth of ~200 m. The analysis of the continuous time series provides strong evidence of the seasonal signal in speed, spiciness, and depth of the CUC and NPEW cores, with a time resolution unprecedented to date. Most of the variance of water mass and flow properties is explained by the annual cycle. The phase shift between the depth of the NPEW core and the strength of the CUC suggests that remotely generated Kelvin waves are responsible for the seasonal variability observed off northern Baja California.

We analyzed the peak spring tidal current speeds, annual mean tidal power densities ( $TPD$ ) and annual energy production ( $AEP$ ) obtained from experiment 06.1, referred as the “HYCOM model” throughout, of the three dimensional (3D), global model HYCOM in an area covering the Baja California Pacific and the Gulf of California. The HYCOM model is forced with astronomical tides and surface winds alone, and therefore is particularly suitable to assess the tidal current and wind-driven current contribution to in-stream energy resources. We find two areas within the Gulf of California, one in the Great Island Region and one in the Upper Gulf of California, where peak spring tidal flows reach speeds of 1.1 m per second. Second to fifth-generation tidal stream devices would be suitable for deployment in these two areas, which are very similar in terms of tidal in-stream energy resources. However, they are also very different in terms of sediment type and range in water depth, posing different challenges for in-stream technologies. The highest mean $TPD$ value when excluding TPDs equal or less than 50 W m⁻² (corresponding to the minimum velocity threshold for energy production) is of 172.8 W m⁻², and is found near the town of San Felipe, at (lat lon) = (31.006–114.64); here energy would be produced during 39.00% of the time. Finally, wind-driven currents contribute very little to the mean $TPD$ and the total $AEP$ . Therefore, the device, the grid, and any energy storage plans need to take into account the periodic tidal current fluctuations, for optimal exploitation of the resources.