DELAWARE BAY, at the mouth of the Delaware River, is a large arm of the sea, 75 miles long, 20 miles wide between Cape May on the N. and Cape Henlopen on the S., and 30 miles wide in the middle. The navigation is difficult and dangerous, being interrupted by many shoals. Its low and sandy shores were without harbours until the construction of the breakwater within Cape Henlopen, noticed under the State of Delaware.