To reach the Delta, you can take the public boat from Tulcea, which is slow and sort of irregular, or get a private speed boat (which is fast, but windy!). There are three main Danube channels - St George, Sulina and Chilia. I explored all three, and I found the northern one, Chilia, to be the most interesting. And the most remote. It borders on Ukraine to the north.
Periprava, a small, remote, Russian old believer Russian, I found to be the most interesting settlement on the Danube Chilia arm. You see, Sulina, in the middle of the Delta, is interesting and historic, but it is too big. The lounge bars, the the wide paved streets, the schools - you just feel you are in a big town even if there are just a few cars. St George is somewhat in between - both remote and civilised, yet not as charming as the villages to the north. And much more commercial and touristy.
Periprava, with its old Russian, Siberian-style wooden houses and churches, the remains of the old communist-era labour camp, the Letea sub-tropical forests, the thousands of wild horses, the fishermen, the birds... there is so much to explore and enjoy here, away from the crowds of usual tourist destinations. Oh, and did I mention the wild empty sand beaches?
The food is mainly fish, coming from the Danube and from the Black Sea. It is served with a bit of fresh vegetables that people grow in their backyards. It's rustic and tasty and fresh.