What was done
In a study of coral microatolls growing on reef flats of the Cocos Islands (96°52'E; 12°08'S), the authors reconstructed a history of sea level based on annual coral skeletal density bands manifest by X-radiography, supplemented by annual fluorescent bands made visible by ultra-violet light.

What was learned
It was determined, in the words of the authors, that "there has been little net rise in sea level in the eastern Indian Ocean during the 20th century."  In fact, mean sea level there, according to the coral data, rose only 2.3 to 3.3 cm.  This result is much lower than the 10 to 24 cm rise inferred for global sea level over this period from aggregate tide-gauge records corrected for postglacial rebound; but it is consistent with results obtained over the past decade from TOPEX satellite altimetry for a 2° x 2° grid centered on Cocos.

What it means
The authors state that "the significance and persistence of the accord between the TOPEX and microatoll sea-level signal for Cocos and their mutual divergence from prevailing 'global' sea-level rise trends cannot yet be resolved with the available data."  Until this discrepancy is resolved, therefore, it would probably be wise to withhold judgment on this important topic.  Perhaps low-lying coastal areas and islands are not in as great a danger of being submerged as many climate alarmists are claiming.