Parnidis Dune

Wikipedia: The Curonian Spit (Lithuanian: Kuršių nerija, Russian: Ку́ршская коса́ (Kurshskaya kosa), German: Kurische Nehrung, Latvian: Kuršu kāpas) is a 98 km long, thin, curved sand-dune spit that separates the Curonian Lagoon from the Baltic Sea coast. Its southern portion lies within Kaliningrad Oblast, Russia and its northern within southwestern Lithuania. It is a UNESCO World Heritage Site shared by the two countries
We took the ferry across and the did some orienteering training. The terrain was incredibly complex forested sand dune terrain, including WW2 fortifications. Very exciting.
We then travelled down to Nida, which is right on the Russian border. Hoping to not repeat the earlier escapade, we didn't stray too close to it. Visiting several geocaches and the enormous sundial that is just behind where the photograph is taken from