New to Civ: How do I explore the seas to find other countries in Civ V?

I gather that I have to research a certain technology before I can spawn boats which can travel further than 2 or 3 tiles from the coast, is that right?

I have only met about half of the Civilizations on my map but I've explored one big island, I need to go and find the others on other islands, just can't get there yet.