Greece is more than Athens — it's dozens of islands from Crete to Santorini, often reached by ferry. Here's which eSIM to get so your internet works in the capital and on the islands alike.
For a week in Athens with navigation and social media, 3–5 GB is usually enough. For an island-hopping trip — Crete, Thessaloniki, Santorini, Mykonos — with ferry bookings and maps on the go, get 8–10 GB or more.
Coverage is fast and reliable almost everywhere in Athens, Thessaloniki and Crete. On smaller islands, coverage is generally good in port towns and tourist areas, but can be weaker on remote beaches and in mountain villages.
On most routes between major islands, coverage holds up for nearly the whole crossing, except for stretches of open sea far from shore — that's normal and not specific to any one carrier.