Coupled records of Sr/Ca and oxygen isotope ratios (δ 18 O) of coral skeletons have been used to produce quantitative estimates of paleo-sea surface temperature (SST) and δ 18 O of surface seawater that can in some cases be converted to sea surface salinity (SSS). Two fossil corals from Kikai Island in the subtropical northwestern Pacific, a location affected by East Asian summer and winter monsoons, were analyzed to investigate differences between mid-Holocene and present-day SST and SSS. At 6180 cal yr BP, SSTs were roughly the same as today, both in summer and winter; δ 18 O seawater and SSS values were higher both in summer (+0.5‰, +1.1 psu) and in winter (+0.2‰, +0.6 psu) than modern values. At 7010 cal yr BP, SSTs were slightly cooler both in summer and winter (−0.8 and −0.6 °C), whereas δ 18 O seawater and SSS had higher values in summer (+0.3‰, +0.6 psu) and in winter (+0.8‰, +1.9 psu) than present-day values. These results are consistent with other marine records for the mid-Holocene of the low and midlatitudes in the northwestern Pacific. Such regional conditions indicate that the East Asian summer and winter monsoons were more intense in the mid-Holocene, which was likely a function of the mid-Holocene insolation regime.