This dataset contains the measurements of sea level made by Nevil Maskelyne on the Island of St. Helena from 12 November to 22 December 1761, as published in his Philosophical Transactions of the Royal Society paper of 1761 (https://doi.org/10.1098/rstl.1761.0100). The data values presented were transposed from the information in Maskelyne's original paper into the data file included with this submission by the authors of this dataset. The data have been subjected to various types of quality control by the authors including, in particular, consistency of the tidal content of the sea level time series with modern expectations, and the data have been studied within a modern reanalysis (submitted for publication). The purpose of this dataset is to make the Maskelyne measurements more accessible in an electronic form for the benefit of future researchers.