The last interglacial (LIG; similar to 130 to similar to 118 thousand years ago, ka) was the last time global sea level rose well above the present level. Greenland Ice Sheet (GrIS) contributions were insufficient to explain the highstand, so that substantial Antarctic Ice Sheet (AIS) reduction is implied. However, the nature and drivers of GrIS and AIS reductions remain enigmatic, even though they may be critical for understanding future sea-level rise. Here we complement existing records with new data, and reveal that the LIG contained an AIS-derived highstand from similar to 129.5 to similar to 125 ka, a lowstand centred on 125-124 ka, and joint AIS + GrIS contributions from similar to 123.5 to similar to 118 ka. Moreover, a dual substructure within the first highstand suggests temporal variability in the AIS contributions. Implied rates of sea-level rise are high (up to several meters per century; m c(-1)), and lend credibility to high rates inferred by ice modelling under certain ice-shelf instability parameterisations.