Before planning the trip, check some ideas of activities that the island has to offer.
If it is your first trip to Azores and if you do not have much time, I recommend to start from visiting Sao Miguel island. It is enough 3-5 days to explore main sightseeings of this main island.
Here I prepared some ideas of "must visit" places and "must do" activities.
1. Unique black volcanic sand beaches - this is one of the top reasons to visit the islands.
My favorites on Sao Miguel island are 2 beaches:

Santa Barbara beach, that has gorgeous sunsets and a famous surf spot.

Mosteiros - with an incredible view of the cliffs in the ocean of the same name and it is also the best spot on the island for whale watching.
2. Azores is hydrangea paradise.
The high flowering season of this incredible plant in the Azores is from the end of April to the end of June. It is real hydrangea madness in the form of giant bushes and tunnels of hydrangeas along the roads of the island.
3. Thermal springs on the islands.

In addition to all the other beauties and advantages, the Azores also have unique thermal springs!
On the island of San Miguel in the city of Furnas, there are springs whose waters are saturated with iron and, accordingly, have a number of useful properties.
* Terra Noshtra (Furnas)
* Poça de Beija (Furnas) is my favorite
In addition, there are other sources on the island:
* Caldeira Velha (Ribeira Grande)
And the icing on the cake is the “hot ocean” or natural Japanese bath at Ponta da Ferraria.

4. Tea plantations.
On the island of San Miguel there are the only 2 operating plantations in Europe on an industrial (!) scale:
Porto Formoso and Chá Gorreana.

5. Whalewatching.
Whales can be observed here almost all year round, but the main season comes in the spring and until the end of June. The chances of not seeing them at this time are practically zero.
But make allowances for weather conditions, because at a certain level of wind and waves, observation boats do not leave for safety reasons.
The permanent inhabitant of this area is the sperm whale.
But in the strait between the islands of San Miguel and Santa Maria in the spring, you can often see the blue whale, the world's largest animal, up to 30 meters long and weighing up to 150 tons.
It also takes place in spring and autumn between the islands of Terceira and Sao Jorge.
Together with São Jorge and Pico, Faial Island forms the so-called “triangle”, and Horta is home to one of the main and most dynamic cetacean observation and study centers in the archipelago.
Pico Island is the island with the most established whale traditions.
Go check out my guide for the best free things to do as well as itineraries and travel tips to make your trip unforgettable.