From Eretria you can explore all of southern and eastern Euboea; there are wonderful beaches around Karystos, Styra and Marmari as well as in the vicinity of kymi, not to mention a Venetian castle, a few ancient sites and unspoiled villages to whet your appetite.
You can equally head northwest for Halkida (Chalkis), the bustling capital of the island, and from there either continue on to the northern part of the island or rejoin the national road.
If you decide for the mainland, you can always change your mind and return to northern Euboea by ferry from Arkitsa or Glyfa. So, back on the national road, which after we've crossed Boiotia brings us back to the sea again, this time it's the Northern Euroboean Gulf. The sign for Malessina and Theologos marks our first contact with it; then the rood begins to follow the coast at Skala tis Atalantis and Livanates.
Here the coastline begins to change personality. Gentle, cultivated hills and valleys give way to steep, wooded mountains; the shoreline contracts. We're heading towards the famous pass at Thermopylai. Hotels, cafes and restaurants proliferate, too, their customers attracted by the lovely scenery and pleasant bathing.
We pass Arkitsa. From here you can pop over to Aidipsos, a long - established health spa - resort where steaming sulphurous waters bubble into the sea. A spectacular new road now joins Aidipsos with the pretty villages of Rovies and Limni down the west coast.
Or you might choose to view the northern coast from Agiokambos, where you can catch a ferry for Glyfa on the mainland, to Pefki ("Pine"), which as the name implies is surrounded by trees. In fact, most of this part of the island is densely wooded, some of it even lush.
But let's continue our tour of the mainland. Agios Konstantinos is next. This is where you can catch the ferries and Flying Dolphins to the Sporades, or you might choose to stay put.
"Agios" and it's next door neighbour, Kammena Vourla, are popular for family holidays. The beaches are calm and there are plenty of entertainment possibilities along the waterfront. Kammena Vourla's fame began as a result of its mineral waters; long a favourite holiday spot with Greeks, it now attracts tourists of all nationalities. Try the beach at Agios Serafeim, further up the coast. Now we come to Thermopylai, where the statue of Leonidas reminds us of how 300 Spartans fought desperately to hold the pass against the Persians. In Greek the main means "Hot Gates", indicating that here too hot springs provide treatment for all sorts of ailments. Pressing on, we arrive at Stylida with its small port and extended olive groves.
Just before it to the west lies Lamia, capital of Fthiotis, a lively but undistinguished market town with a 14th century Frankish castle. The mountains in this region are well worth investigating, however, for a glimpse of what Greece is like without tourist development.