This dataset includes geochemical and densitometric data from an early Little Ice Age (LIA; 1273–1332±4 CE) Porites microatoll slab collected in November 2017 from Arno Atoll, Marshall Islands. 230Th-U-dating was performed at GEOMAR, Kiel, Germany. Powder samples were extracted along the growth axes of the coral at 1 mm resolution (9.5 samples per annual band). Trace elements were measured using an Agilent 720 (axial) inductively coupled plasma optical emission spectrometer at MARUM, University of Bremen, Germany. Mean Sr/Ca of JCp-1 standards measured along with this coral was 8.914±0.012 mmol mol-1 (n = 11; 1 sd). Stable isotopes were measured using a Finnigan MAT 252 mass spectrometer equipped with an automated Kiel III carbonate preparation device at the Stable Isotope Laboratory of MARUM, Bremen, Germany. Skeletal density was measured using a γ-densitometer at the Goethe University, Frankfurt am Main, Germany. The data are provided in their raw form (i.e., without linear interpolation to an evenly spaced time domain) and are referenced by sample number and distance (mm) along the respective sampling axis.