We've rented a motorbike for the day for 200 baht (4 euros) and had a look on the other side of the island. We're leaving Koh Tao today and heading for Koh Phan Ngan by boat. That's the island where the full moon party takes place, but I will carefully try to avoid this party. too much noise and tourists.
By the way I can receive text messages on my French phone, so if anyone needs to contact me urgently, it's +33686448920. I dont receive call though.