George,
We passed through in 2006 on our way from
Texas to the
Bahamas so we have only been there once. The SE side of Garden key next to the lighthouse is the most protected spot. It is well worth the visit. The holding is not so good in
coral rubble over rock. Dive on your
anchor and set it by hand. Also stock up well before you head out. There are no supplies and you might be there longer than anticipated. We were stuck for 8 days due to 30-35
knot NE winds. Our next stop was Key West so it would have been tough if we were on a schedule. Here is a link to pictures of our visit
Dry Tortugas Have fun.
Dave