In 2012, Hurricane Sandy split Fire Island into two islands, creating a new inlet to the bay behind it. Contrary to the fears of many, there is no evidence suggesting that the opening of the new inlet has increased the risk of of flooding to the mainland (see the following USGS study, Hurricane Sandy Impacts Did Not Contribute to Subsequent Storm Flooding). In fact, scientists say that the breach actually helps clean the bay waters, and fishermen are seeing positive changes.
The following video is courtesy of National Geographic.