02/08/2016 Newsround

Good afternoon, you're live with Newsround,

Ayshah here with a look at what's going on today.

Sinking low - this sinkhole opens up in a garden in Australia.

And flying high - thousands of mayflies take

over a bridge in Poland.

But first he's one of the most famous faces of Team GB.

And with the Olympic Games just three days away

Tom Daley has landed in Rio - a moment he's been working

towards for eight years.

Hi, I'm Tom Daley and over the last eight years,

I've been working as hard as I possibly can to make my third

Olympic dream come true.

It started back in 2008 in Beijing, when I qualified when I was 13 years

old and managed to compete when I was 14.

And then in 2009, I won the World Championships.

Ever since I got the taste of being on top of the world,

I've always wanted to win an Olympic gold medal.

Then in London 2012, it was the home Olympics,

the most exciting thing ever.

There was 18,000 people coming to support me.

My friends, my family, millions watching at home.

So there was a lot of pressure.

To come away with an Olympic bronze medal was something that

I've always dreamt of.

And then after that into 2013, was one of my toughest

years of diving.

I was injured with a bad tricep.

I was so terrified every single time I went to the diving board.

But I managed to get through it, and I took a little bit of time out.

I took six weeks to go and travel the world and do what I wanted

to do, to try and reset my brain.

Then I came back to diving, and wanted a little bit of a change.

So I moved to London, and I had a new coach.

And since then, I haven't really looked back.

I've been working as hard as I possibly can.

And then I also had to learn a new dive, which is a three

and a half somersault with one twist.

And that's something that was a bit of a risk, actually,

to learn a new dive so close to the Olympic Games.

But I feel like I'm in my peak form, peak shape.

I just want to go out there and win an Olympic gold medal.

Good luck, Tom.

Toymakers have been getting into the Olympic spirit too,

with this massive Lego model of Rio.

More than 50 people from three different countries were involved

in building it, they used around 953,000 pieces.

They've created famous Rio landmarks, Olympic stadiums,

and even athletes competing in the games.

Now this isn't an Olympic sport, but it's just as impressive!

13-year-old Ally set himself the challenge of going to every

single London Underground station in just one day.

Jenny has the story.

Lets go!

It's just after 10am, and Ally is on a very special

journey with his mum and dad.

They're trying to travel through every tube station

on the London Underground network, all 270 of them.

We've just been through the 67th station.

67th station, OK.

And next is London Bridge.

They started in Chesham, more than 30 miles from the city

centre, where they only had the tube driver

for company.

Over 7000.

?7,000 and 84p.

Wow.

So we've gone up 1000 in a day.

Very good.

They're raising money for a cancer research charity after Ally's older

brother died earlier this year.

It was obviously very hard for me.

He unfortunately passed away after all the treatment

in March this year.

So, I decided to make sure no one else has to go through that,

that I would raise funds.

Difficult, but it's quite a positive thing.

We've had so much support from so many people.

All through London, people we've never met,

Transport for London.

The charity itself.

It's all been very feel-good in that respect.

So yeah, it's hard, we wish we weren't having to do this.

But it's also been a really, really positive experience as well.

It was a lot of hard work, but Ally made it to his final stop

and completed his challenge.

Well done Ally.

Staying with an underground theme - kind of.

This sinkhole has appeared in the back garden of

a house in Australia.

It opened up to show swirling water and grew to eight metres wide.

Thankfully no-one's been hurt.

It's thought it could have been caused by an old mine shaft.

And from sinking low to flying high - these incredible pictures show

hundreds of thousands of mayflies taking over a bridge

in south-eastern Poland.

They're not harmful to humans and it's believed to show

the environment is clean, because mayflies live

in fresh water.

That's it for now, Newsround is back tomorrow morning at 7:40.

See you soon.