As an adventurer, is international roaming free in Bulgaria with my UK or US SIM card?

The situation for free roaming in Bulgaria depends on your origin. As an EU member, 'Roam Like at Home' benefits apply to EU citizens. However, if you're from the UK (Post-Brexit), many UK carriers like O2, Vodafone, or Three have reintroduced daily roaming charges, which can quickly accumulate. For US travelers with carriers like AT&T or T-Mobile, expect costly international daily passes. An eSIMAdventures plan is often a more economical and straightforward way to stay connected, allowing you to focus on climbing in the Rila Mountains, not roaming fees.