The greatest contrast occurs if you enter from the north and exit towards the south or vice-versa. Cañadas del Teide is a gigantic caldera spanning 17 km (10.5 miles) across, from which the summits of Pico Viejo and Mount Teide rise up to 3,718 m (12,198 ft), making this Spain’s highest point and the third tallest volcano in the world. Its snowy white peak contrasting with tongues of black lava petrified on the slopes is a unique combination that never fails to surprise.
If you come in springtime, look out for the unmistakable colour of the red bugloss, a unique plant that can grow up to 3 m (9.8 ft) tall and bursts into bloom with thousands of tiny bright red flowers. Another of the world’s unique treasures you will find here is the Teide violet, a proud symbol of the Park that grows only above altitudes of 2,500 m (8,200 ft). If you manage to see one, consider yourself extremely lucky.
If the landscape and vegetation seem taken from another planet, the fauna is no disappointment. Keep an eye out for the smallest of creatures. Most of the insects here cannot be found anywhere else. You will also come across unique reptiles, such as the Tenerife lizard, the Tenerife gecko and the Canarian lizard. For bird lovers, prepare to see kestrels, great grey shrikes and some endemic species such as blue chaffinches. There is also a mammal that is worthy of special mention, though it was introduced by man: the Corsican mouflon. Spotting one is quite a challenge, as they tend to hide from human view.
Source: Tenerife Tourist Board