If you are interested in volcanoes. A visit to La Palma to see the effects of the sept 2021 eruption, is a must-see.

The western Islands had also Laurisilva evergreen forests. An humid ecosystem relict as close as one "European rainforest" as you can have. Very "Jurassic Park" vibes.

The small El Hierro Island not much far away is worldwide famous as diving spot. All Islands are good to dive, but in El Hierro is easier to spot big fishes. Whale sharks and Manta rays are not uncommon in the correct months.

Very good places also to do Whale Watching. Dolphins and the tropical species of Pilot Whales are easy to watch in Tenerife, Palma, Gomera or El Hierro. Sperm whales frequent the area also.

In short Tenerife is the most complete in terms of variety of ecosystems and Lanzarote is probably the most spectacular geologically. If you want nature avoid the most crowded destinations that receive zillions of tourists searching for beach and booze.

Been there many times, and even more in Fuerteventura. Both are very peculiar islands. Fuerteventura is kinda an offshore Sahara extension. You can walk into huge dune parks, and go to beaches with no one on sight for kilometers. Many locations will give you an otherworldly feeling. Nature, specially vegetation, in the eastern, newer islands, is not very abundant, but still plenty of things to be amazed to. Volcano visits in Lanzarote are bit touristy but still a must. You can eat volcano cooked chicken and see some geothermal action. If you are into volcanoes La Palma had a three months eruption last year.

All in all is a place ideal for quiet vacations, with plenty of amazing beaches and where time seems to flow slower. I will go again.

I was there in 2017, the landscape is stunning. I visited the volcanic park of Timanfay and smaller volcanoes you can go into like el Cuervo. There are also other nice places to visit like the Mirador Del Rio and (if you like it), the Saramago home museum. I also visited Tenerife, which while much more touristy, is also much cheaper and also has the Teide Volcano which you can visit.

I’ve been to Lanza a few times and, like another commenter, Fuertaventura even more times

Great island for a holiday for sure. Lanza is more bio diverse with lot of greenery in the north and then just barren rock desert in the south. I’ve mountain biked around the south quite a lot, it’s fun but go prepared, the rocks destroys bike components like nowhere else I’ve ridden (including the French Alps).

There is a sports resort over towards El Golfo in the south west that looks pretty great and I’ve heard good things about.

The surfing in the west is good but if you want surf then Fuerta is the island to go to.

FV is just pure rock desert everywhere and it’s a surf and kite surf paradise for sure. Corralejo in the north is a nice town and easy access to flag and glass beach for surf and also the north shore via the dirt track to El Cottilo. I have mountain biked in FV but it’s a boring cross country struggle fest and the wind is killer.

Clearly the production crew of Star Wars agreed about the Canaries as the North of FV was used as a location for some of the Star Wars movies as well.