Every visit to the Roque de Los Muchachos is different; the clouds are never the same! Of course, most of the time there's actually never a cloud in the sky.
But when there is:

One day the clouds may be very high in the sky, diffusing the light of the sun and occasionally coming down to cover the Roque and all the views. Other days you'll be above the cloud and you can only see the tips of the mountains, sometimes the neighbouring islands of Tenerife, La Gomera and El Hierro.

Other times, the island will be surrounded in a low cloud layer far below and as far as the eye can see, whilst the island itself is cloudless and baking in the sun.
Sometimes (mainly in winter) the Caldera will be a seething mass of apparently boiling clouds, sometimes bubbling over and spilling down over the sides. The sky above a rich deep blue.