The basic trade-off
Ferries are cheaper, take longer, and offer the experience of arriving at a Greek island the way Greeks have arrived for 3,000 years — by sea. You see the island grow on the horizon. You watch other islands pass. The ferry itself is a social space full of Greek families, backpackers, and the occasional priest. There's a reason Greeks themselves still take ferries when they could fly.
Flights are faster, more expensive (sometimes), and remove the experience entirely. You leave Athens at sea level and arrive at sea level on an island 50 minutes later. The plane is the plane. Nothing memorable happens.
But the trade-off isn't always what it seems. For some routes, flights are actually cheaper than ferries (especially booked early). For others, ferries are dramatically faster. The right answer is route-specific.
Always fly: Athens to Crete
Athens to Heraklion (Crete's capital): 50 minutes by plane, €40-90 one-way. Athens to Heraklion by ferry: 8-9 hours, €40-55. The ferry isn't materially cheaper and costs you a full day. Unless you specifically want the overnight ferry experience (which is fun once — sleep in a cabin, wake up in Crete), fly.
Athens to Chania (western Crete): same calculus. 1 hour by plane, €60-100. The ferry takes 9 hours overnight. Always fly.
Aegean Airlines and Sky Express both fly multiple Crete routes daily. Booking 2-3 weeks ahead gets you under €70 one-way. Day-of can be €120-180. Book early.
Always ferry: Athens to Hydra, Spetses, Aegina (Saronic Gulf)
These nearby islands have no airports. Hydra is 90 minutes by hydrofoil from Piraeus (€32-42). Spetses is 2 hours (€40-55). Aegina is 70 minutes (€18-30). Even if planes flew here (they don't), the trip from central Athens to these islands is a 'leave at 8 AM, arrive at 10 AM' kind of journey. Ferries are the only option and they work fine.
These islands also benefit from the ferry experience — Hydra particularly, where the no-cars rule means you arrive at the harbor and immediately are 'on the island' in a way airports don't deliver.
Mostly fly: Athens to Rhodes, Corfu, Lefkada (long routes)
Athens to Rhodes: 1 hour by plane (€60-120) vs 16-18 hours overnight by ferry (€45-75). The math overwhelmingly favors flying. Some travelers do the ferry for the romance of arriving at the medieval port at dawn — fair, but you lose two days of vacation.
Athens to Corfu: 1 hour flight (€60-110) vs no direct ferry (you'd need to drive 5 hours to Igoumenitsa first, then ferry 90 min). Always fly.
Athens to Lefkada: actually no Lefkada airport — fly to nearby Preveza (Aktion airport) or Athens-drive (4.5 hours). For most travelers, fly to Preveza and rent a car at the airport.
It depends: Athens to Santorini, Mykonos, Paros, Naxos
These are the routes where the ferry-vs-flight question gets interesting because both options work and serve different travelers.
Athens to Santorini: 50 min by plane (€60-150 booked early, up to €280 day-of) vs fast ferry 5 hours (€78-105). Slow ferry 8 hours (€58-72). Flying is faster but you trade 50 min in the air for 90 min total airport-to-island-center time, while the ferry is 5 hours total but ends with you arriving directly at the port (which IS the destination on Santorini — Athinios port is below Fira). For a 5-night Santorini trip, flying once each way is usually right. For tighter budgets or for the romance of the slow ferry, the ferry works.
Athens to Mykonos: 50 min by plane (€55-120) vs fast ferry 3-4 hours (€60-85). Ferry from Rafina (a port closer to the airport than Piraeus) is 30-40 minutes faster. For most travelers, fast ferry from Rafina is the most practical option — similar total time as flying, much cheaper, more frequent.
Athens to Paros: 4 hours fast ferry (€55-72) vs Athens-Paros has limited flights (Paros's small airport, expensive seasonal flights €100-180). Ferry is the right answer almost always.
Athens to Naxos: 3-4 hours fast ferry (€55-70). Naxos has a small airport too but very limited flights. Ferry is the practical answer.
The tactical breakdown by trip length
Short trips (3-5 nights, single island): fly when possible to maximize time on the island. Worth paying €60-100 extra to gain 4-6 hours of vacation. Crete, Rhodes, and Corfu specifically benefit from flying.
Medium trips (7-10 nights, 2 islands + Athens): mix and match. Fly the longer leg, ferry the shorter one. Example: Athens → fly to Crete (saving the day) → ferry from Heraklion to Santorini (3.5h, easy) → fly Santorini back to Athens.
Long trips (10+ nights, multi-island): ferries make more sense. You've got time to spare. The ferry-hopping itself becomes part of the adventure. Routes like Athens → Mykonos → Paros → Santorini work well as a ferry chain.
Booking specifics that matter
Book ferries 5-14 days ahead in peak summer (June-August). Fast-ferry economy seats sell out first. Use Ferryhopper or Direct Ferries — both aggregate the operators (Blue Star, SeaJets, Hellenic Seaways, Aegean Speedlines).
Book flights as early as possible. Aegean and Sky Express prices fluctuate dramatically. Flexible-date searches help. Booking 4-6 weeks ahead in summer is the sweet spot for reasonable prices.
If you have flexibility on dates, ferry prices are similar across the season (€55-85 for most fast-ferry routes), but flight prices can vary 3x — €60 in shoulder, €180 in peak. Sometimes the flight is cheaper than the ferry; sometimes 4x more. Check both.