"Inland Eastern Europe" typically refers to the six countries with no coastline—fully surrounded by land in the continent's eastern half.
Of the original list, only Belarus, Czech Republic, Hungary, and Slovakia are fully landlocked. Poland and Ukraine have coastlines.
If including Moldova (often grouped here), that's five landlocked. Serbia (Balkans) makes six—but it's usually "Southeast Europe."
Landlocked status shapes economies: higher trade costs, dependence on neighbors' ports/rail, vulnerability to transit disputes. Belarus, Czechia, Hungary, Slovakia all rely on German, Polish, or Romanian infrastructure for maritime access. The Danube (Bratislava, Budapest) provides riverine relief.
Geography isn't destiny—but it's a persistent structural factor.