The dataset contains wide-angle seismic data from 6 ocean bottom nodes (OBX-90, GEOSPACE) collected during RRS James Cook cruise JC254 in November 2023. The data were acquired at the Semenov-1 Hydrothermal Field region of the Mid-Atlantic Ridge at 13°30'N, and were shot in two sequences (SEM1 and SEM1B). Two GI-guns were used as seismic sources, each with a total volume of 210 cubic inches (105 cu. inch generator, 105 cu. inch injector chamber). The data were recorded at a sampling rate of 2000 Hz (500 µs), with a shot interval of 8 s at a ship speed of 5 knots, resulting in shot interval of ~20.5 m. The data are provided in raw SEGY format, cut into four components (three geophone channels and one hydrophone channel). The SEGY file has a trace length of 10s and 20000 samples. This dataset was collected with an aim to derive a seismic velocity structure of the SEM-1 seafloor massive sulphide deposit region. The aim was to understand the interplay between tectonic faulting, magmatism, 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.