The Samos harbour had a great strategic importance, but it didn´t have a spring which supply it with drinkable water.
The task that Eupalinus received from the tyrannus of Samos was to dig a tunnel through the mountain to be used as a aqueduct between the northern  entrance N and southern one S.
In order to save energy, the tunnel had to be as straigh as possible. In order to spend less time, he decided to start digging from both sides. To take measurement on the horizontal plan, the references had to be at the same level. In the map.
The activity we propose consists of two parts:
A) Find the exact location of the excavation. It is an exercise of great precision, since the minor error at
the beginning would make the tunnels not to find each other or not to do it a straight way.
B) Locate the point where the North and South drillings should meet if they work at the same pace
on both sides.
We indicate some suggestions on the map, none of them on how to get to Samos …

Two versions of the activity are proposed, Samos tunnel and step by step

Authors: Bernat Ancochea, José María gallego & Javier Martín