The ELVES project investigates the Hikurangi subduction interface below and offshore the Wellington region, New Zealand. This area is currently “locked”, building up stress that will be released in a large, destructive subduction thrust earthquake. The onshore GeoNet network is largely blind to small offshore earthquakes, and even large earthquakes are poorly located, hindering understanding of the hazard posed by the offshore subduction zone. We deployed 20 broadband ocean-bottom seismometers (OBS) from the NFSI pool to study seismicity and to determine the three-dimensional seismic velocity structure. The OBS were deployed in November 2023 and recovered in January 2025 (18 were successfully recovered). The data quality is excellent. Here we present preliminary analyses that include determining the orientation and tilt of the seismometers from recordings of distant earthquakes and ambient seismic noise, and relocating selected earthquakes recorded by the land-based GeoNet network. From this analysis, we identify smaller earthquakes that were not located by GeoNet. When the earthquakes are fully analyzed, we expect them to feed into improved seismic and tsunami hazard estimates. Follow-up work will include determining the 3-dimensional seismic velocity structure of the locked Hikurangi margin using ambient noise, surface-wave and body-wave tomography, teleseismic receiver functions, and shear-wave splitting data.