The dataset contains 3D wide-angle seismic data from 18 ocean bottom nodes (OBXs) collected during RRS James Cook cruise JC254 in November 2023. The data were acquired at the 1330 Oceanic Core Complex (OCC) and the Semenov Hydrothermal Field region of the Mid-Atlantic Ridge at 13°30'N, and were shot in six sequences (SEM4A to SEM4F), along 15 profiles in total. Two GI-guns were used as seismic sources, each with a total volume of 355 cubic inches (250 cu. inch generator, 105 cu. inch injector chamber. The data were recorded at a sampling rate of 2000 Hz, with a shot interval of 20 s at a ship speed of 4 knots, resulting in shot interval of ~30 m, with no stop during profile turns. The data are provided in raw SEGY format, cut into four components (three geophone channels and one hydrophone channel). This dataset was collected to derive a seismic velocity structure of the 13°30'N OCC. The aim was to investigate the crustal or mantle lithologies in the 13°30'N OCC and to understand the interplay between tectonic faulting, magmatism, alteration and hydrothermal circulation at the ultramafic-hosted hydrothermal systems along slow-spreading ridges. The data were collected as part of a NERC-funded strategic research project called 'Ultramafic-hosted mineral Resource Assessment (ULTRA)', grant reference NE/S004068/1. The data were processed and interpreted as part of a PhD studentship hosted by the University of Southampton, awarded to Szu-Ying Lai, and funded by Equinor A.S, Norway.