The visitor can approach Lasithi mainly through its airport or through the port of Heraklion that is 65 kilometers away from Agios Nikolaos (50 minutes by car). There are plenty of daily itineraries of ships and airplanes from Athens as well as from other European cities (in the summer.
Agios Nikolaos has a port which is mostly used as call of many cruise ships during the summer.
Siteia (70 km away from Agios Nikolaos) has an airport connected to the airport of Athens on a daily basis during the summer season; moreover it accepts a limited number of charter flights every summer.
You can find more information about the airport of Siteia on the website of the Municipality of Siteia here.
If you are in Athens or on an island of the Dodecanese or the Cyclades, you can travel to Siteia by ship.