A word of warning about Santorini - there are many, many steps. The caldera is hundreds of feet high. There is a cable car down to the harbour at Fira and there are well used, but steep and twisting paths, or you can take a mule ride. In Fira itself there are steps and constant changes of level. The same applies to the neighbouring villages and to Oia. Anyone with any walking difficulty at all, would be advised to bear this in mind.
This picture is taken from a boat and shows Fira clustered on top of the rim of the caldera.
If you take a volcano tour, your tour will end at either Fira or Oia. If you choose to end your tour at Oia to watch the sunset, the boat will drop you off at the port below Oia village. You have to walk up a steep zigzag incline of 250 steps before you reach Oia village. By that time, you will be panting and exhausted and will need to catch your breath.
Take this option of dropping at Oia port only if you are fit and healthy with no medical or physical disability. Otherwise, you should elect to end the tour at Fira where you can easily take a bus or taxi to Oia.
Steps are everywhere in Santorini. Even if you avoid the steps down to the harbour, you can’t avoid going up and down steps everywhere. The centre of Fira is reasonably flat along the edge of the Caldera, but the side streets drop away as you turn inland, and of course, if you venture into the narrow paths and lanes just below the Caldera rim you’ll be climbing up and down all the time. So remember to wear sensible shoes, and look where you are treading – in places the paths are uneven, and you don’t want to turn an ankle and ruin your holiday, do you.
It's not so much a warning, but just a bit of friendly advice. The streets in the main town of Fira are cobbled and rather steep in places, with lots of steps up and down. If you want to enjoy your wonder about the shops, leave the high heels at home, otherwise, it's just too much like hard work!
Many of the hotels in Fira, Firostefani and Imerovigli are ranged down the cliffside and you reach them by long, fairly steep steps and hilly paths. This can be a problem if you have a lot of heavy luggage. Your hotel may have a porter, but the poor guy is likely to be overworked, and in most cases you'll have to handle your luggage yourself. We passed numerous people struggling to get luggage up the hills and steps looking very hot and tired.