Las Canteras beach’s specs speak for themselves; 3.5 km of golden sand sheltered behind a lava reef in the city with the most pleasant climate in the world (according to Syracuse University).
The area behind the reef is also a no-take reserve so it's packed with fish; they're not stupid you know.
I counted over 40 species of fish during one swim the other day along with plenty of octopus. The water is clear and never gets below 18ºC even in winter.
Jump in at Playa Chica in the middle of the beach, swim out to the reef, then head south towards the La Peña rock that sticks out between the sea and the reef.
Watch out for schools of multi-coloured parrotfish, huge groups of cruising striped bream, feeding schools of golden porgies, and scorpionfish lurking on the rocks. The octopus are everywhere but you have to look carefully to spot one; look out for little semi-circles of rocks as they like to have a wall in front of their cave.
For a immersive experience, float about by the rock on the shore where Luis Morote street meets the sea; it's where people feed the fish so you are surrounded by hungry bream and porgies.