Santorini was always short of water. The cycladic climate with the strong winds and the high summer temperatures would make someone think that no plant can leave on the island. The answer to the fertility of the island is the night moisture (that provides a little of water to the plants) and the excellent quality of the pumice - volcanic soil. Santorini produces the best wine in Greece and according to many funs in the world. During the turkish ocupation Santorini was paying greater taxes to the sultan than all the other Cycladic islands together and it was because of the high prise of Santorinian wine.
The small tomatoes is a must (you will think that you eat a tomatoe for the first time) and generally all agricultural products are smaller, but better...
The last famous product of the island is fava, based on peas, unique in Greece.