To gain information on the chemical parameters of deep water in the western North Atlantic, water samples were taken using a Niskin bottle deployed at five stations at the RMS Titanic wreck site (stations: 0075, 0079, 0080, 0081, 0082 - deepest samples at station 0081: 41.7335576, -49.9467401, 3,831 m water depth) and at one station at a newly-explored seamount ridge (station 0083: 41.5975604, -49.439188, 2,870 m water depth) during the OceanGate expedition aboard AHTS Horizon Arctic, 15 June - 25 July 2022. The ridge is part of Seamount U in Pe-Piper et al. (2007). A total of 20 water subsamples were collected and analysed for total alkalinity (TA) and dissolved inorganic carbon (DIC). TA was analysed using an Apollo SciTech AS-ALK2 alkalinity titrator and DIC was analysed using an Apollo SciTech AS-C3 inorganic carbon analyser. The aragonite saturation state was calculated using the CO2SYS system (Lewis and Wallace, 1998).

Corresponding author: Roberts, J Murray