Nida (German: Nidden) is a town in Lithuania and located on the Curonian Spit. First settled by German in the 15th century AD and part of Prussia before 1945. It is very popular with German tourist because the German writer Thomas Mann had a summer house which he regular visited in the early 1930s.
Most travellers arrive via ferry from Klaipeda. There's an ecological fee to enter the national park (which Nida/Neringa is part of) - 30LT/car in summer and 10LT the rest of year. The land border to Russian province Kaliningrad at Nida - Morskoje has a 24h service. Ecological fee - 250RUB. Travel to Russia requires a valid Russian visa. The port has no regular passport/customs services, contact Nida border station, Smiltynės plentas 23, Nida in advance, tel.: +370 469 52 284.
There used to be very scenic and reasonably fast ferry from Kaunas, operated by Nemuno Linija.
You can rent a bicycle and ride all the way to Juodkrante (about 30 km), visiting Preila and Pervalka en route. The bicycle track goes by the Curonian Lagoon for about 15 km, then through a pine forest and finally by the sea, letting you to see lots of beautiful sceneries. Don't forget to stop by the Vecekrugas dune (~1 km before Preila) and the Dead Dunes (Negyvosios kopos) (near Pervalka).
First of all - fish. Try some smoke-dried eel or bream.