Bird Island is western point of Sunset Beach, North Carolina - they are connected - you can walk or bike down beach from Sunset - of you could get there by boat. Sunset is first beach community north of South Carolina line. Google "Sunset Beach Bird Island". Location of Kindred Spirit's Mailbox ("landmark" on Bird Island) is at 33 51.293 N; 078 32.116 W; plug that into Google Earth; there is geocache further west on island that many people visit.

I have family friends with a beachhouse at Sunset but until this subject came up on this thread, I did not know that Bird Island was known for a nude beach. After seeing that said here, I asked some folks and, sure enough, it is known for that, although the impression I was given is that there never are very many people there total and very few nude beach goers, if any. I do know that the mosquitos can be ferocious at times there so you need to bring an appropriate amount of DEET.