A Bulgarian short-stay visa valid throughout Schengen can support travel to Greece and Romania within its conditions. Check territorial coverage, validity dates, authorised stay and entries before departure. Direct crossings from Bulgaria into these countries are internal Schengen journeys, although temporary controls and police checks remain possible. Carry your passport and relevant documents. If the route passes through a non-Schengen country such as Serbia, you will leave and re-enter Schengen, which can make a single-entry visa insufficient. Previous Schengen stays and vehicle insurance coverage also need separate checks.