The wind was picking up again, making the swell grow.

Almost as soon as I dived in to start swimming, I felt a stabbing pain in the left side of my back.

I shouted up to Nicola, my trainer, to ask what was going on. She said that it was likely that I was compensating for the pain in my shoulder by over-twisting my back in the rougher waters.

This was going to be a long, sore day of swimming.

It made me realise that nothing is certain about this swim; it isn't over until I touch the white cliffs of Dover.

The longest swim I have ever completed prior to this was 203km (126 miles) down a Norwegian fjord where I benefited from the protection of the mountains on either side, which is far from the case with the English Channel.

I still have an awfully long way to go, and 135km is far from a fait accompli.

When I reached one and a half hours, my back was in substantial pain, so I shouted up to the skipper how far we had gone.

It wasn't quite far enough, I was going to have to swim another 30 minutes to reach the target distance for today. I gritted my teeth.

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The wind started to pick up even more, every time I took a breath I could see our FXTM banners flapping along the side of the boat.

We were approaching one of the south coast's largest windfarms, and when I breathed to the left, I could see the turbines whipping around with Brighton a small spec in the background. I started to count the windmills to try and distract myself from the pain.

That last half an hour felt like three full hours, I managed 26 minutes before calling it quits for the day. I covered 13.43km (8.34 miles).

I thought I'd been imagining the pleasant smells wafting over from the boat, but as I got out, Denise presented me with a plate of homemade flapjacks and a buttery, cheesy jacket potato.

The stress of today's swim began to melt away, even if my back was still sore.

As I was finishing up and starting to stretch out, a red object bobbing away to the port side caught my eye. It looked like a helium balloon.

Our first mate, Rowan, turned the boat around and we started chasing it through the waves.

After a few minutes, it was close enough for me to dive in and grab it out of the water. I was right - it was heart shaped, helium balloon.

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It was a stark reminder that what goes up, must come down. Just because it doesn't come back down in your garden where you can recycle it responsibly, doesn't mean it's not an issue. It becomes someone else's issue.

Or something else's - a seabird, a fish or a dolphin. It becomes their issue, because as that heart-shaped balloon begins to break down into smaller pieces of plastic, it starts to look very appetising to sea creatures who can't tell the difference.

It blocks their stomachs and the string attached to the balloon strangles or chokes them - horrible ways for any animal to die.

If a smaller fish eats the smaller pieces of balloon, that plastic will just go up the food chain until it lands, hidden, on your plate. Then you eat it too, because it doesn't fully biodegrade.

The long-term impact of microplastics in humans isn't yet known, but I very much doubt it would be a good thing for us. What we do know is the impact that it's having on our oceans.

Single-use plastics must end.

Every plastic straw, every plastic water bottle, every plastic bag, every piece of plastic cutlery and crockery, every piece of plastic packaging - and every plastic balloon.

There are better ways to show your love for somebody than this.

8.34 miles (13.43km) - Total 246.56 miles (396.8km)