Asmara International Airport is the only major international gateway to Eritrea. Eritrean Airlines, Egyptair, Ethiopian Airlines (when the route is operating), and a handful of Gulf carriers fly into Asmara from Cairo, Dubai, Khartoum, and a few European cities. Flights are not cheap and timetables shift; check carefully ahead of booking.
Visitors need a visa in advance, which generally needs to be applied for at an Eritrean embassy several weeks before travel. There is also a separate travel permit needed for any trip outside of Asmara — this is dealt with at the Tourism Ministry on arrival and usually takes a day or two to issue.
Overland borders with Sudan and Ethiopia have been intermittently closed and reopened over the years. Travel by land is not predictable; flying is the realistic option for most travellers.