Name: British island bagging.

Age: Quite young.

Island bagging? How do you bag an island? You just go there, really.

Where? To an island – a British one.

Any island? Well, it needs to be a proper one. That means 74 acres (30 hectares) in area, or 100ft (30 metres) high, of which there are apparently 706.

And that’s it, island bagged? Yes, a bit like Munro bagging.

Isn’t that what Tony Curtis did in Some Like It Hot? You’ve got the wrong Monroe. Munro bagging is climbing mountains in Scotland over 3,000ft, then ticking them off. People also bag lesser mountains, called Corbetts, Grahams, Marilyns …

Marilyn! Are you sure this has nothing to do with Norma Jeane? Quite sure: it’s about mountains. [See footnote]

I thought you said it was about islands? Sorry, you’re right, it is.

So are islands the new mountains? I suppose so, in a way.

And bagging them is the latest craze? Craze might be pushing it, but it’s certainly a thing. Last year, the Highland and Islands Transport Partnership looked into launching an island passport scheme, whereby tourists would earn a stamp for each one they visit.

Are the passports red? I want one: where do I apply? That’s not actually up and running, but people are doing it anyway. A book called Scottish Island Bagging by Helen and Paul Webster is published next month. There are also plenty of baggable isles south of the border and in Northern Ireland. The Sunday Times reported that the leading island bagger is Rob Woodall, on 518. The leading female bagger has 130. Bee Leask, who has bagged 60 islands, has nearly 100,000 followers on her Bumblebambi Instagram account.

I’m in. How do I get to these islands? That’s the beauty of it: it is entirely up to you. By ferry, swim, luxury yacht, stand-up paddle board, walk …

Walk? And if it turns out I’m not the Messiah? Loads of Britain’s islands can be reached on foot at low tide, probably most famously St Michael’s Mount in (and sometimes off) Cornwall and Holy Island (AKA Lindisfarne) in Northumberland. Just make sure you get back in time, and don’t disturb the puffins at Lindisfarne.

Brilliant, especially as soon no one will be able to go abroad, because of visas and the pound being worth diddly squat. Plus no flying, so the environment wins, too.

Do say: “Save the planet, with a gannet.”

Don’t say: “But I just want to go somewhere hot, with a pool and paella ...”

• This footnote was added on 3 September 2019. The name Marilyn (for a hill that has a topographical prominence of at least 150 metre) was coined as an ironic contrast to the designation Munro, which is homophonous with (Marilyn) Monroe.