Things to do/see in Santorini

Go to the Santorini forum here: http://www.tripadvisor.com/ShowForum-g189433-i245-Santorini_Cyclades.html. You'll see a green stripe at the top of the page. Locate and clik on "Things To Do".

If you're interested in history you can visit Ancient Thira, the ruins of the ancient city. You can also visit the Akrotiri excavations. If you enjoy visiting small villages you can visit Pyrgos and Megalochori. You could also visit different beaches. We visited Kamari and Perissa. We rented a car for a day and fit in most of these sights. Also, Oia is breathtaking during the day as well!

Hi, first of all July is the perfect month to be there. So many things to do there, I'll give you some info:
a. The view from Profitis Ilias (Monastery)
b. Walking from Fira to Imerovigli (through Firostefani)
c. Breathtaking view from Faros (lighthouse) at Akrotiri
d. A few hours tour in Thirasia. I'll stay a little bit here because Thirasia is the island 1 mile from Oia, and around 40 years ago in time. It has a unique view to Santorini and a great landscape. You go there by boat (great feeling being among the two calderas). Look in TripAdvisor for an organized tour because only this way you will be able to combine them both. To me that is the best tour you shouldn't miss if you go in Santorini.
e. Akrotirion museum (Ruins of a city before the earth quick around 1531 bc)
f. Walk around to at least one Kasteli (old castle) (Pyrgos, Oia, Emporio)
g. Go to the church which is behind Skaros (The big rock at Imerovigli). It has amazing view
I understand that 4 days in not much but d,f and e are MUST DO THINGS.
Enjoy

Rick's book mentions a few other things, slightly more fleshed out in the Greece book than the Med Cruise Ports book. Akrotiri Archeological site rates a star but the museum in town that holds finds from that site rates 2 stars. I would spend one day at a beach, with nothing else planned to interrupt the relaxation. I also enjoyed a caldera boat trip several years ago, when I stayed in Oia and walked down the stairs in the morning to the Amouda port, not the main port; check schedules locally.

I disagree. July is far from the perfect month. It's way too hot for outdoor activities, especially walking long distances.

We've been here (staying in Firostefani) for the last three days. Here are some of the highlights from our time: 1) hiked from Firostefani to Oia (start early in the morning and bring water). It's an absolutely beautiful hike. We finished it off by walking through Oia and then walking down the caldera trail to Ammoudi Bay to go for a swim. Followed that up with lunch on the water and then took a taxi back to Firostefani. 2) did a half day seakayaking trip around the southern end of the island, visiting the red, white and black beaches. This was a guided trip with Santorini Seakayaking and they did a great job. The trip included lunch and all your gear, including snorkeling gear to snorkel during the break. 3) rented a car, drove to the lighthouse for incredible views, visited a couple of wineries and then went swimming at Kamari beach (bring beach shoes for the rocky beach). Oh, and drove up to and walked around Pyrgos and the castelli.

We've been here (staying in Firostefani) for the last three days. Here are some of the highlights from our time: 1) hiked from Firostefani to Oia (start early in the morning and bring water). It's an absolutely beautiful hike. We finished it off by walking through Oia and then walking down the caldera trail to Ammoudi Bay to go for a swim. Followed that up with lunch on the water and then took a taxi back to Firostefani. 2) did a half day seakayaking trip around the southern end of the island, visiting the red, white and black beaches. This was a guided trip with Santorini Seakayaking and they did a great job. The trip included lunch and all your gear, including snorkeling gear to snorkel during the break. 3) rented a car, drove to the lighthouse for incredible views, visited a couple of wineries and then went swimming at Kamari beach (bring beach shoes for the rocky beach). Oh, and drove up to and walked around Pyrgos and the castelli.