The sea is at 23 degrees and the beaches have emptied: October is the month Lanzarote keeps for itself

Here is something summer visitors do not know and residents do not volunteer, so as not to spoil it: the sea around Lanzarote is at its best right now. In October the water averages 22.7 degrees, with lows around 21.9 and highs touching 23.3. Together with September, it is the best stretch of the year for swimming.

Why the sea is warm as the air cools

It sounds like a contradiction and it is elementary physics: water heats slowly and cools more slowly still. An ocean takes months to absorb the summer's heat, and as long again to give it back. The upshot is that the sea's temperature peaks about two months later than the air's.

In plain terms: in July the sun beats down but the water has not finished warming. In October the sun is gentle and the sea is at its best. And the beaches, meanwhile, have emptied.

Where to go this month

If you want still water and a seabed that slopes gently — that is, if there are children — head south. Playa Dorada and Playa Flamingo, in Playa Blanca, are sheltered and calm nearly always. Playa Grande and Playa Chica, in Puerto del Carmen, have everything a few steps away.

If you want to swim properly, Las Cucharas in Costa Teguise and Los Pocillos in Puerto del Carmen are long enough for real lengths.

If you want natural pools, Punta Mujeres in the north: rock basins filled by the tide, clear and sheltered water. In October, without the August crowds, they are a different thing altogether.

If you want the place worth the journey, Playa Francesa, on La Graciosa: you get there by boat from Órzola and then on foot, and the water is the kind that does not look real.

Two things to know regardless

The wind does not care about the temperature. It always blows on Lanzarote, and the north and west coasts — Famara, La Caleta — remain surf sea rather than easy swimming, even at twenty-three degrees. For swimming: south and east.

Read the flags. The Atlantic here has real currents even when it looks like a swimming pool, and in October there are fewer lifeguards on duty than in August. If the flag is red, it is red even if the water is twenty-three degrees and the sky is perfect.