Almost 1.9 million homes in the U.S. — roughly 2 percent of the nation’s housing stock, worth $882 billion — could be underwater by 2100 with six feet of sea level rise,according to a new report by Zillow , an online real estate database. One in eight Florida homes, representing $413 billion in property value, could flood by the end of the century. In Hawaii, one in 10 homes are at risk and in New Jersey, one in 13. The new analysis is based on climate projections and mapping from the National Oceanic and Atmospheric Administration, as well as Zillow’s database of 100 million U.S. properties. It found coastal cities, such as Miami and Honolulu, are particularly vulnerable to sea level rise. More than 1 in 6 Boston homes could be underwater by 2100. These estimates don’t include commercial buildings or government properties.