\"When you think of the Florida Keys, icebergs are probably not the first things that come to mind,\" the USGS wrote on Facebook. Among the more mysterious parts of the discovery is the fact that icebergs were flowing south against the Gulf Stream, the report states. That led researchers to conclude a \"large scale but brief\" flood of melted ice water was powerful enough to sweep the ice along. The icy current also helped the icebergs survive long enough to reach subtropical areas, the study found. Explore further Icebergs drifting from Canada to southern Florida©2021 The Charlotte Observer (Charlotte, N.C.) Distributed by Tribune Content Agency, LLC.