1. Ride the subterranean Mail Rail
After standing in somebody's armpit on the Tube – London's overheated, overpopulated transport network – the last thing you'll want to do is pay to go back underground.
However, the Mail Rail isn't your typical tube experience. Between 1927 and 2003, the Post Office's underground micro-railway carried millions of letters a day on a 6.5-mile network beneath the streets of London.
The tracks have lain disused for over a decade, but in September 2017 the Postal Museum reopened the Mail Rail to the public, allowing visitors to board replica rail cars and ride through this once forgotten piece of the city's heritage.
2. Go kayaking on the Thames
The guys at describe themselves as follows: "we like water, we like fire and we like to explore". In their night-kayak-across-London experience (£55), they embrace the former and the latter.
Organised to coincide with the falling tide, you set sail from the beach at Vauxhall Bridge Road (yeah, London has mini-beaches) eastwards towards Greenwich.
There are many ways to glimpse the city's blockbuster sights, like the Houses of Parliament, St Paul's Cathedral and Tower Bridge, but none is more romantic or invigorating than with the slosh of the Thames beneath you.
Katherine Futers/Secret Adventures
3. Experience the surreal House of Dreams
Kitsch, multicoloured, eccentric. Visiting the is unlike any other experience in London.
The life's work of artist Stephen Wright is a surreal and overwhelming collection of plastic dolls, bleach bottles, Christmas decorations and vinyl records, taking up every inch of his Victorian East Dulwich home.
Wright became a follower of outsider art, the movement that eschews what is "tasteful" and "acceptable", after becoming disillusioned with mainstream art and textiles after a lifelong career in design.
The House of Dreams is only open on certain days and by appointment, so check before you go.
Michael Vaughan/House of Dreams
4. Go for a walk in the woods
Back in the day, the Great North Wood sprawled all the way from the Thames to Croydon. While most of this has been lost to development over the centuries, the enchanting neighbouring Sydenham Hill and Dulwich woods are the closest ancient woods to central London.
Embrace the labyrinth of tall trees and don't worry about trying to figure out where you are. Part of the joy of the woods is the birdlife; keep an eye out for green parakeets, woodpeckers, tawny owls and sparrowhawk.