I don't know if it helps, but you might check out
http://terraserver.microsoft.com

I searched for Dry Tortugas and came across four entries (each with an
aerial photo and topo map option... although, the topo maps I looked at
didn't show any land).  When you follow a link to an aerial photo, you might
have to scroll or zoom to find something useful, but it might be worth a
shot.

I was fortunate enough to have a friend that worked out there so I had AC and
hot showers. They do have primitive camping and there is a boat that makes the
run.

http://www.fortjefferson.com/camping.htm

Dennis

Been a long long time since I was last there, and things may have
changed, but:

Ft Jefferson is the only bit of land that is not protected. When I was
last there, there were no facilities. That includes potable water and
toilets. I hear they do now have some amenities. Too bad.

The best way to get there is to go over to the airport on Block Island
and hire a seaplane. They fly out right on the deck and take a
meandering course over the local sites. Great views of wrecks, sealife,
blahblah.

It used to be a truly remote spot and the only person you'd see was the
one caretaker at Ft. J. And you'd have a hard time finding him.

"Dry" Tortugas?  I guess you have to bring your own alcohol...