Pack carefully if you are minded to explore the Tagus Abyssal Plain, a region which those in the know are apt to abbreviate as TAP — not to be confused with a Portuguese airline. It is also the name of the territory which must inevitably be traversed if you are making for Josephine Seamount.

So you think you know your way around Europe? We thought we did until we discovered there’s another parallel geography out there. How little we know about the topography and toponyms of the seas and oceans around Europe and more widely! Pressed to locate the Seine Basin, one might assume that it is somewhere near Paris. Think again. It is actually a submarine feature off the coast of north-west Africa.

Sail east from Sardinia towards Naples and you’ll pass close to a mountain named after the Russian physicist Sergey Vavilov, who also enjoys the distinction of having half a crater on the moon named after him. Only half, because the crater is named in honour of both Sergey and his brother Nikolai. But the submarine mountain in the Tyrrhenian Sea is Sergey’s alone. It is a very respectable mountain, one that would surely be celebrated for its rugged beauty if it just popped its head above the water.