The holidays are upon us.

You need some great days out in London.

But you've done all the big stuff.

The Science Museum? Natural History? London Zoo?

Been there. Got the t-shirt. Holiday after holiday.

You need somewhere new to make memories with the kids.

Without hiking halfway across the country.

And battling every other London family to get there.

So what do you do?

Well here's 10 secret London days out, you probably haven't done.

And which should capture your kids imagination.

1. Go Up A Windmill

Yep, there's a real windmill in London. Who knew?

Brixton Windmill is just 10 minutes walk up Brixton Hill from the tube.

And is a big winner for any kids who love machines.

We were wowed by its gears!

Plus it's easily combined with yummy food in Brixton Village Market. Or the fab Brockwell Park - a short scoot away - which has a lido, cool playground, sandpits & splash pool, BMX track and more.

The windmill isn't open everyday but there are regular tours and family activities.

An alternative is Wimbledon windmill on the lovely Wimbledon Common.

2. Explore Underground Caves

22 miles of caves under London?

Really? Yep, really?

And you can visit them!

But be warned, the Chiselhurst Caves are pretty spooky!

So you may want your kids to promise a cuddle when you scream!

Handily, the caves are very close to Chiselhurst station.

With trains from London Bridge, Cannon Street and Charing Cross.

3. Go Wild By the Thames

If you want to go wild without leaving London, head for Rainham Marsh.

Right by the Thames, it's home to wild owls, peregrines, weasels and much more.

And for a massive day out, combine it with Rainham Hall a lovely National Trust house close by.

4. Mudlark at Blackfriars

There's so much history in the Thames.

And everyday an awful lot of it washes up on the foreshore.

If you head down the riverside steps at Blackfriars - in front of Tate Modern - you'll find old china, clay pipes, all sorts of old metal and some slightly gory bones!

It's a brilliant activity to combine with a visit to the Museum of London. You get the real low down on London's history and may even spot some of your finds in the museum.

Check tide times with the BBC. It's best to go a bit before lowest tide.

5. Join the Lavender Harvest

Did you know London used to be home to the world's largest lavender harvest?

Nope? Me neither. But it was!

And you can actually still join the lavender harvest every summer.

The lavender is in flower from June.

To see it in all its glory visit Mayfield Lavender Farm.

Or join the pick your own harvest at Carshalton Lavender.

6. Paddle in Forgotten Rivers

So many of London's old rivers are hidden underground these days.

But you can still paddle in the lovely River Cray.

It cuts through the beautiful Tudor Hall Place, which hosts fun stuff for kids in the holidays.

Or head to the river Darent in Eynsford - just outside London - where you can combine paddling in the ford with a Roman Villa, a Norman Castle, Eagles or a world garden!

Cool huh?

7. Hunt Dinosaurs

Got dinosaur mad littlies?

Then head to the dinosaurs at Crystal Palace.

They've been marauding through Crystal Palace Park since the 19th Century!

There's also a small farm in the park.

And amazing views over London.

To find out more about the Crystal Palace dinosaurs read this review from local mum Jemma.

8. Dig for Fossils

Older London kids can actually dig up their own fossils.

Right here in London!

The lovely Abbey Woods, next to the ruins of Lesnes Abbey, is actually one of the most important sites worldwide for Angel Shark teeth.

On our first visit, we collected over 30!

You can find all the details for visiting here but basically, there's free public access and you just need to rock up with a couple of buckets, spades and seives!

9. Build Sandcastles on the Beach

When the sun is scorching but you can't make the seaside, head to the beach at Ruislip Lido.

It does get busy on a hot day, but there's sand a plenty for sandcastle building.

Plus a miniature railway round the lake. And a splash park.

AND the lake is surrounded by fantastic woodland where you can easily get away from any crowds and cool down climbing trees in the shade.

10. Pick Your Own!

From June onwards, there's fruit and veg a plenty to pick on London's farms.

The big old grand daddy of London PYO farms is Garsons.

And award winning Parkside in Enfield is very popular.

You can get the low down on Parkside from a local mum here.

But we also have a soft spot for Hewitts a small old family farm in south London. It's a bit scruffy and there's no grand garden centre or fancy facilities but that's part of its charm.

If you're driving, you can also combine Hewitts with visits to Lullingstone Roman Villa or Darwin's House which are 10 minutes or so away.

Hopefully, some of these secret London days out with kids have tickled your fancy.

For more ideas, check out this list of 30 historic London houses with great grounds to run around in that are perfect for a big London day out with kids.

Or for some money saving ideas, try this list of 101 free days out in London with kids.

Or head over to my Family Fun London page on Facebook.

Everyday I share the latest cool London events for kids...