Syros is the ferry hub of the Cyclades — more ferries pass through Ermoupoli than any other island in the group, which means it is easy to reach and makes an excellent starting point for island-hopping.
By ferry: Multiple daily sailings connect Syros to Piraeus (Athens's main port) in approximately 4 hours on fast ferries, or longer on conventional ferries. There are also regular connections to Mykonos, Naxos, Paros, Tinos, Santorini, and most other Cycladic islands. The main ferry operators are SeaJets, Blue Star, and Golden Star Ferries — book through Ferries.gr or directly on the operators' websites.
By air: Syros has a small airport (SY/JSY) about 5km from Ermoupoli, served by domestic flights from Athens (around 45 minutes). Olympic Air and Sky Express operate this route, with more frequency in summer. The airport is convenient but flights are limited out of high season.
From Athens: Flying from Athens airport to Syros is the quickest option. The ferry from Piraeus is slower but more atmospheric and often cheaper.