Chesapeake Bay Conceals A 35 Million Year Old Impact Crater

There is a 35 million year old impact crater from an extraterrestrial impact in Chesapeake Bay (which is in the vicinity of Washington D.C.). 

This particular impact isn't associated with any major extinction event extreme enough to find in the paleological record, although it surely had lesser climate and impact effects, but it is a good illustration of how a body of water can conceal an impact crater.