Don’t panic! I shiver and Granddad glances down at me.

‘Are you okay?’ he whispers.

I nod.

I never thought we’d actually be here.

Steve tells us how panicking can be dangerous, that if anything goes wrong the most important thing is to remain calm. Then he tells us not to worry, because once we get used to it, breathing under water will become second nature, just like when we breathe fresh air.

I wrap my arms around my body and try to stop myself shaking.

Jake, why did you think of this?

‘Okay,’ says Steve. ‘I’m just going to show you the equipment and some simple tips. This is the mask.’ He holds a blue mask up to his face. ‘It covers your nose and your eyes, as you’d expect. Now when you first get in the water it may fog up, but all you have to do is let some water in – I’ll show you how in a minute . . . The next thing to tell you about is the regulator – now contrary to what many people think, the worst thing you can do when scuba diving is hold your breath.’

Let water into your mask? Don’t hold your breath? He’s teaching us how to drown, not dive. I can’t do it. I can’t. I look up at Granddad and hope that he’s feeling the same, but he’s got his fingers over his nose.

‘That’s it,’ says Steve. ‘Just blow – that’s how you clear your eustachian tube, which is important otherwise the pressure will build and it’ll feel like your head is going to explode.’

Everyone laughs except me.

‘Felix, did you understand that?’ asks Steve.

No. I shake my head.

‘Like this,’ says Granddad. He clamps his fingers over his nostrils. I do the same. ‘Now just blow inside your head. Like when you blow your nose.’

‘Okay,’ says Steve. ‘I’m sure you can’t wait to get on with it.’

Oh we can.

‘Right, let’s have you all in the water. Just walk forward until your toes are gripping the edge.’

I stand still as everyone else edges forward.

‘Granddad.’ I grab his elbow just as the others splash into the pool. ‘We don’t have to do this.’

‘Don’t worry,’ he replies. ‘I’ll be fine.’

You might be, but I’m not.

‘Felix, Francke. Are you joining us?’ Steve is in the water with a mask pushed up on his forehead and everyone else is treading water while looking at me.

‘Of course we will join you!’ says Granddad as he edges forward.

I want to pee.

I want to run.

Water splashes over my legs as Granddad jumps into the water.

‘Come on, Felix,’ says Steve. ‘Just you now.’

‘Yes,’ says Granddad, wiping water out of his eyes.

‘Just you now. In you jump.’

‘Yes. Just jump.’