How far is it from the cruise port on Santorin Greece to Fira on the same island?

There will be a ton of taxis and buses waiting to take you to Fira. The island itself is very small and there are buses that can take you between the towns. If you are staying the night, often your hotel will pick you up.

There are two ports in Santorini. The Old Port (below Fira) and the New one. If the boat stops at the Old Port you will either walk to Fira (30' walk up the 600 something steps if you are fit) or use the cable car (takes a few minutes, depending on how many people are waiting).

Now, if the boat stops at the New Port I am sure there will be buses arranged for you to leave the port. The New Port is about 30 minutes by car from Fira. There are taxis at the port BUT many times they are not enough. So, better take the buses arranged for you if you don't want to waste any time. You don't have to be with them all the time just ask where you have to meet them on the way back and go on your own.

Have a good time!

If you are taking a larger ferry you will most likely be going to new port where there are many buses that are at the port when you arrive. 10 minutes you'll be in fira bus station. make a right from the bus station parking lot and you can walk from there to fira town which is right up the hill. If you have luggage with wheels this is a small hassle,so pack light.other wise its a huge hassle. it cost about 5-7 euro for a bus and atleast twice that for a cab. in any case it should not be missed.

have a blast